Okay so here is my dilemma. I obviously can't bind in gym class and all my sports bras can barely hold my chest because it's nearly impossible to find sports bras large enough for me and I absolutely refuse to wear a normal bra. I also can't really find a loose enough shirt. I have a lot of body issues in gym because I almost constantly see guys watching my chest as I run or jump and it makes me not want to participate. I need some advice for helping hide my chest better in gym of there is one. Thank you.
I think the best thing to do would be to do your exercises at home, whether that means buying equipment or changing your exercise routine altogether. As you know you can't bind while exercising, and if sports bras don't work on you then working out at home seems like the only option for you. I know it may be a bit more troublesome to set things up and change your routine, but at least you won't have to get bothered by other people, or feel more dysphoric.
It might be worth getting a binder a size bigger than the one you currently have. Or underworks do binders with less layers of compression which should be less restricting, might be worth looking into.
I can't say I think it's a good idea to wear a binder while exercising, even if it is a size up. Have you looked at the Underworks Minimizing/Binding Sports Bra? It's essentially a high compression sports bra, which means it should be safe to exercise in while still minimizing your chest.