Pie chart issues in flutter

I'm using the fl_chart package to create an interactive Pie Chart for my application. Although the design came out fine, I'm facing the following issues with the functionality:

1. Tapping on a particular PieChartSectionData doesn't always select it and even tapping repeatedly doesn't help. It's always two out of the three that are tappable. Please note that the functionality works as it should for all the sections but there is no indication suggesting that the section tapped on was clicked. As defined in my code, every tap on a section should increase the radius and it's font size to make it stand out from the rest.

2. Every time a PieChartSectionData is clicked, it is supposed to navigate to a new page after a delay of 500 milliseconds. Although this works as expected, I cannot seem to come back to the previous page that has the Pie Chart on it using the phone's back button on the very first click. It is only after repeated clicks that it takes me back to the original page.

3. The chart seems to be clickable even beyond the PieChartSectionData. So like let's say if I tap an inch away from one of the sections, it tends to take me to that other page I need to navigate to. This shouldn't be the case.

Here is my code:

class ToDoListPieState extends State<ToDoListPie> {
  int? index;
  double? percent;
  int? taskCount;

  @override
  Widget build(BuildContext context) {
    final provider = Provider.of<TodaysTaskList>(context).getToDoList;

    // TODO: implement build
    return Stack(
      children: [
        PieChart(PieChartData(
            borderData: FlBorderData(show: false),
            pieTouchData: PieTouchData(
              touchCallback: (FlTouchEvent event, pieTouchResponse) {
                setState(() {
                  if (pieTouchResponse == null ||
                      pieTouchResponse.touchedSection == null) {
                    index = -1;
                  }
                  index = pieTouchResponse!.touchedSection!.touchedSectionIndex;
                });
                Future.delayed(const Duration(milliseconds: 500), () {
                    Navigator.of(context).push(MaterialPageRoute(builder: (context) => TaskList()));   //This here is the event where clicking on a section should take us to the next page
                  });
                  print('Index: $index');     //This prints even if we click away from a section

              },
            ),
            sectionsSpace: 5,
            centerSpaceRadius: 80,
            sections: [
              PieChartSectionData(
                  color: Colors.blue,
                  title: provider['upcoming'].length.toString(),
                  value: double.parse(provider['upcoming'].length.toString()),
                  radius: index == 0 ? 40 : 30,
                  titleStyle: TextStyle(fontSize: index == 0 ? 25 : 16)),
              PieChartSectionData(
                  color: Colors.amber,
                  title: provider['today'].length.toString(),
                  value: double.parse(provider['today'].length.toString()),
                  radius: index == -1 ? 40 : 30,
                  titleStyle: TextStyle(fontSize: index == -1 ? 25 : 16)),
              PieChartSectionData(
                  color: Colors.red,
                  title: provider['previous'].length.toString(),
                  value: double.parse(provider['previous'].length.toString()),
                  radius: index == 1 ? 40 : 30,
                  titleStyle: TextStyle(fontSize: index == 1 ? 25 : 16))
            ])),
        Positioned(
          left: 0,
          top: SizeVariables.getHeight(context) * 0.18,
          right: 0,
          bottom: 0,
          child: Column(
            children: [
              FittedBox(
                fit: BoxFit.contain,
                child: Text(
                  '${provider['upcoming'].length + provider['today'].length + provider['previous'].length}',
                  style: Theme.of(context)
                      .textTheme
                      .bodyText1!
                      .copyWith(fontSize: 25),
                ),
              ),
              Text(
                'Tasks',
                style: Theme.of(context)
                    .textTheme
                    .bodyText1!
                    .copyWith(fontSize: 18),
              )
            ],
          ),
        )
      ],
    );
  }
}

Any help will be appreciated!