Dena, thank you for the suggestions! Sadly I'm very insecure about my arms (even in t-shirts), so the sleeveless hoodies aren't really something I'd like to try, and I'm not very fond of vest jackets, but thank you!
Elis, thank you for the reassurance. I'm pre-everything so it was probably obvious to them that either a) I'm trans or b) I'm just a butch lesbian that wants to look like a guy.
I wear a binder currently, I find that it works much better than the sports bra method (and it's actually safer), and when I say double bind I mean layering another binder or a sports bra over the one I'm already wearing. But thank you!