Button doesnt stick where its supposed to be – Flutter

I have a bottomNavigationBar that contains an inputText and Buttom widgets that will be used in a chat application. The expected behaviour is that inputText expands itself when multiple lines are written, and the button get sticked to the bottom of the component

Padding(
        padding: EdgeInsets.only(bottom: MediaQuery.of(context).viewInsets.bottom+3),
        child: Row(
          children: [
            Expanded(
              child:Padding(
                padding: EdgeInsets.fromLTRB(5, 0, 0, 5),
                child: SizedBox(
                  width: MediaQuery.of(context).size.width * 0.8,
                  child: TextField(
                    keyboardType: TextInputType.multiline,
                    minLines: 1,
                    maxLines: 5,
                    // expands: true,
                    style: TextStyle(
                        fontSize: 20
                    ),
                    decoration:   InputDecoration(
                        border:  OutlineInputBorder(),
                        contentPadding: EdgeInsets.fromLTRB(10, 0, 0,0)
                    ),
                  ),
                ),
              ),
            ),
            Padding(
              padding: EdgeInsets.fromLTRB(5, 0, 0, 5),
              child:Stack(
                children:[ 
                  Container(
                    width:  MediaQuery.of(context).size.width * 0.2,
                    // height: MediaQuery.of(context).size.height * 0.045,
                    child: ElevatedButton(
                      onPressed: () {  },
                      child: Text("asdf"),
                    ),
                  ),
                ],
              ),
            ),
          ],
        ),
      ),

The code works for inputText part, the problem is that the button got sticked to center of inputText height, and I want it to be in the bottom