Can't reduce size of an elevated button

I am trying to reproduce Apple memo recorder button. Right now, I am trying to reduce the size of Stop Button. First, I have tried without the SizedBox and then with. I am getting the same result.Even if embedded in a SizedBox, I can not achieve what I want. Please, can somebody tells me what I am missing? Thank you.

Container _RecordButton(){
    return Container(
        height: 90,
        width: 90,
        decoration: BoxDecoration(
          border: Border.all(
            width: 4.0,
            color: Colors.grey,
          ),
          shape: BoxShape.circle,
        ),
      child: Padding(
          padding: EdgeInsets.all(4.0),
          child:  isRecording == false?
          _createRecordElevatedButton() : _createStopElevatedButton()),);
  }


  ElevatedButton _createRecordElevatedButton(
      {IconData icon,  Function onPressFunc}) {
    return ElevatedButton(
        onPressed: () {
          if (isRecording = false){

            setState(() {
              isRecording = true;
            });

        }},
        style: ButtonStyle(
        shape: MaterialStateProperty.all(CircleBorder()),
        padding: MaterialStateProperty.all(EdgeInsets.all(20)),
        backgroundColor: MaterialStateProperty.all(Colors.red), // <-- Button color

            /*overlayColor: MaterialStateProperty.resolveWith<Color>((states) {
          if (states.contains(MaterialState.pressed))
            return Colors.red; // <-- Splash color
        }*/));

  }

  SizedBox _createStopElevatedButton(
      {IconData icon,  Function onPressFunc}) {
    return SizedBox(
      height: 14,
      width: 14,
      child: ElevatedButton(

          onPressed: () {
           /* if (isRecording = true){

              setState(() {
                isRecording = false;
              });

            }*/
            },
          style: ButtonStyle(
            fixedSize: MaterialStateProperty.all(Size(10,10)),
              shape: MaterialStateProperty.all<RoundedRectangleBorder>(
                  RoundedRectangleBorder(
                      borderRadius: BorderRadius.circular(16.0),
                      side: BorderSide(color: Colors.red)
                  )
              ),

            padding: MaterialStateProperty.all(EdgeInsets.all(20)),
            backgroundColor: MaterialStateProperty.all(Colors.red), // <-- Button color

            /*overlayColor: MaterialStateProperty.resolveWith<Color>((states) {
            if (states.contains(MaterialState.pressed))
              return Colors.red; // <-- Splash color
          }*/)),
    );

  }

Wrap your elevated button with container and give height and width accordingly.

 Container(
              decoration: BoxDecoration(
                  shape: BoxShape.circle,
                  border: Border.all(color: Colors.grey)),
              child: Container(
                  padding: EdgeInsets.all(7),
                  width: 50.0,
                  height: 50.0,
                  child: ElevatedButton(
                    onPressed: () {},
                    style: ButtonStyle(
                      fixedSize: MaterialStateProperty.all(Size(10, 10)),
                      shape: MaterialStateProperty.all<RoundedRectangleBorder>(
                          RoundedRectangleBorder(
                              borderRadius: BorderRadius.circular(10),
                              side: BorderSide(color: Colors.red))),
                      padding: MaterialStateProperty.all(EdgeInsets.all(20)),
                      backgroundColor: MaterialStateProperty.all(Colors.red),
                    ),
                    child: null,
                  )),
            ),