You have a couple of choices.
1. Go along to get along: If You think getting some speaking experience would be useful in school etc. then turn it to your advantage.
2. As far as getting Baptized goes follow Jesus' example....... Jesus was 30 years old when he was baptized.
4. Field service: "since I have no firm idea what I believe...... it is best if I just support my Aunt in Field service if she wishes."
At the age of 16 you can be emancipated by the Court.
However it is in your best interest to have a roof over your head......... to get a good education and participate in after school programs in sports, music etc. and aim for higher education if only a two year degree.
Keep us posted. Believe it or not we were all thirteen once (lol) some of us raised in a split belief home, or by fully committed believers. Some of us even got baptized early (under 18) to please our parents. That of course became a tragic choice when in a few years we wanted out.
Right now It would serve you well to be kind to your Aunt, helpful around her home and a good student at school.