Help!

I think it's super-early to be thinking about such things as surgery.

In particular, you'll probably just fuel your anxiety by dwelling on it right now.

Instead, concentrate on how you feel. Not just on how large or small you want your chest to be (psst plenty of non-gender-fluid people want smaller chests; a large chest can be a real pain). Rather, about how you feel in terms of gender. Most of the trans people I've met have known really well which gender(s) they are. This isn't invalidating your feelings and experiences. You're you and your experience doesn't have to be identical to theirs. Just telling you what I've seen.

I strongly suggest getting involved with any LGBTQ+ organizations in your area. Maybe through school if you're still going, or even through Meetup if you're past that. If you're not sure about where to go, Google is awesome or talk to a trusted adult - a parent, a teacher, etc. - and they don't have to be queer to know or at least be willing to help you research.

Note: I am not a doctor (hell, I'm not even queer). But I do want you to know that your decision, however it goes, is the right one.