Only one List item displayed when changing screen / page – Flutter

On the add Weight screen I pick a weight and a date and then it gets stored in a list in the Hive database, once I press "Save".
It also returns me to the Homepage, where I would like to depict the stored list items in a ListView.Builder.
I only get the last item on the list and not the whole list.
When I am at the add weight screen, I see that there are more items in the list, but once I return to homepage only the last one exists.

AddWeightScreen

import 'package:flutter/material.dart';
import 'package:flutter/src/widgets/container.dart';
import 'package:flutter/src/widgets/framework.dart';
import 'package:hive_flutter/hive_flutter.dart';
import 'package:intl/intl.dart';
import 'package:weighty/components/my_alert_box.dart';
import 'package:weighty/data/database.dart';
import 'package:weighty/screens/home_page.dart';

class AddWeight extends StatefulWidget {
  const AddWeight({super.key});

  @override
  State<AddWeight> createState() => _AddWeightState();
}

class _AddWeightState extends State<AddWeight> {
  Database db = Database();
  final _myBox = Hive.box("mybox");
  double _currentValue = 0;
  DateTime _dateTime = DateTime.now();
  String formattedDate = DateFormat('d MMM yyyy').format(DateTime.now());
  final _weightController = TextEditingController();

  void _showDatePicker() {
    showDatePicker(
      context: context,
      initialDate: DateTime.now(),
      firstDate: DateTime(2000),
      lastDate: DateTime.now(),
    ).then((value) {
      setState(() {
        _dateTime = value!;
        formattedDate = DateFormat('d MMM yyyy').format(_dateTime);
      });
    });
  }

// add weight from text -  keyboard
  void _dialogNumber() {
    showDialog(
        context: context,
        builder: (context) {
          return MyAlertBox(
              controller: _weightController,
              hintText: "Enter today's weight...",
              onSave: () {
                if (double.parse(_weightController.text) > 200) {
                  _weightController.text = "200";
                }
                setState(() {
                  _currentValue = double.parse(_weightController.text);
                });

                _weightController.clear();
                Navigator.pop(context);
              },
              onCancel: cancelDialogBox);
        });
  }

  //save method
  void _saveWeightAndDate() {
    setState(() {
      db.weightList.add([_currentValue, formattedDate]);
    });
    db.saveData();

    Navigator.push(
      context,
      MaterialPageRoute(
        builder: (context) => const HomePage(),
      ),
    );
  }

  // cancel new weight input
  void cancelDialogBox() {
    // clear textfield
    _weightController.clear();

    // pop dialog box
    Navigator.of(context).pop();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Color(0xFFD9F0FF),
      body: Padding(
        padding: const EdgeInsets.all(20.0),
        child: Column(
          children: [
            const SizedBox(
              height: 28.0,
            ),
            Row(
              mainAxisAlignment: MainAxisAlignment.spaceBetween,
              children: [
                const Text(
                  "Add Weight",
                  style: TextStyle(fontSize: 36, fontWeight: FontWeight.w600),
                ),
                MaterialButton(
                  onPressed: () {
                    Navigator.pop(context);
                  },
                  child: const Text(
                    'CANCEL',
                    style: TextStyle(
                      color: Color(0xff878472),
                      fontSize: 16.0,
                      fontWeight: FontWeight.bold,
                    ),
                  ),
                ),
              ],
            ),
            const SizedBox(height: 30),
            Expanded(
              child: Column(
                mainAxisAlignment: MainAxisAlignment.spaceEvenly,
                children: [
                  Expanded(
                    child: MaterialButton(
                      onPressed: _dialogNumber,
                      child: Text(
                        _currentValue.toStringAsFixed(2) + " kg",
                        style: TextStyle(
                            color: Color(0xFF006B8F),
                            fontSize: 46,
                            fontWeight: FontWeight.w500),
                      ),
                    ),
                  ),
                  const SizedBox(height: 30),
                  Slider(
                    value: _currentValue,
                    min: 0,
                    max: 200,
                    onChanged: ((value) {
                      setState(() {
                        _currentValue = value;
                      });
                    }),
                  ),
                  const SizedBox(height: 30),
                  TextButton.icon(
                    onPressed: _showDatePicker,
                    icon: const Icon(
                      Icons.date_range_outlined,
                      size: 24.0,
                      color: Color(0xff878472),
                    ),
                    label: Text(
                      formattedDate,
                      style: TextStyle(color: Color(0xff878472), fontSize: 18),
                    ),
                  ),
                  const SizedBox(height: 30),
                  ElevatedButton(
                    onPressed: _saveWeightAndDate,
                    child: Text(
                      'SAVE',
                      style:
                          TextStyle(fontSize: 16, fontWeight: FontWeight.bold),
                    ),
                    style: ElevatedButton.styleFrom(
                      elevation: 24,
                      padding:
                          EdgeInsets.symmetric(vertical: 20, horizontal: 80),
                      shape: RoundedRectangleBorder(
                        borderRadius: BorderRadius.circular(30),
                        side: BorderSide(color: Colors.white, width: 2),
                      ),
                    ),
                  ),
                  const SizedBox(height: 30),
                ],
              ),
            ),
          ],
        ),
      ),
    );
  }
}

HomePage

import 'package:flutter/material.dart';

import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:hive_flutter/hive_flutter.dart';
import 'package:weighty/components/weight_tile.dart';
import 'package:weighty/data/database.dart';
import 'package:weighty/main.dart';
import 'package:weighty/screens/add_weight.dart';

class HomePage extends StatefulWidget {
  const HomePage({super.key});

  @override
  State<HomePage> createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  @override
  void initState() {
    //First time ever opening app, Create default data
    // if (_myBox.get("WEIGHTLIST") == null) {

    // }

    //already exists data

    db.loadData();

    // db.saveData();

    super.initState();
  }

  Database db = Database();
  final _myBox = Hive.box("mybox");

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Colors.grey[100],
      floatingActionButton: FloatingActionButton(
        backgroundColor: Color(0xff006B8F),
        onPressed: () {
          Navigator.push(
            context,
            MaterialPageRoute(
              builder: (context) => const AddWeight(),
            ),
          );
        },
        child: const Icon(Icons.add),
      ),
      floatingActionButtonLocation: FloatingActionButtonLocation.centerFloat,
      body: Padding(
        padding: const EdgeInsets.all(20.0),
        child: Column(
          mainAxisAlignment: MainAxisAlignment.start,
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            SizedBox(height: 28),
            Text(
              "CURRENT",
              style: TextStyle(
                color: Colors.grey[500],
                fontSize: 16.0,
                fontWeight: FontWeight.bold,
              ),
            ),
            Text(
              db.weightList.length == 0
                  ? "00.0 Kg"
                  : db.weightList.last[0].toStringAsFixed(2) + " kg",
              style: TextStyle(
                color: Color(0xFF006B8F),
                fontSize: 46.0,
                fontWeight: FontWeight.bold,
              ),
            ),
            SizedBox(height: 40),
            Center(
              child: Text(
                "GRAPH",
                style: TextStyle(
                  fontSize: 16.0,
                  fontWeight: FontWeight.bold,
                ),
              ),
            ),
            Expanded(
              child: ListView.builder(
                itemCount: db.weightList.length,
                itemBuilder: (context, index) {
                  return WeightTile(
                    date: db.weightList[index][1],
                    weight: db.weightList[index][0].toStringAsFixed(2),
                  );
                },
              ),
            ),
            ElevatedButton(
                onPressed: () {
                  print(db.weightList.length);
                },
                child: Text('Print!')),
          ],
        ),
      ),
    );
  }
}

Hive Database

import 'package:hive_flutter/hive_flutter.dart';

class Database {
  //reference the box
  final _myBox = Hive.box("mybox");

  // Empty Weight List
  List weightList = [];

  // void createInitialData() {
  //   weightList = [];
  // }

  //load the date from the db
  void loadData() {
    weightList = _myBox.get("WEIGHTLIST");
  }

  //save the weight

  void saveData() {
    _myBox.put("WEIGHTLIST", weightList);
  }
}