i mean if its too big that is a physical disorder and not just a mental one and would be much more likely to be covered but idk if this is a 'they're too big' or just a 'i'm FTM and i don't like having them'

You have the right to bring this up to a professional and be understood on the matter. You shouldn't have to require a "condition" to have the right to feel comfortable in your own body, and if you pursue this I hope you find a professional who has the human quality to understand said fact and is able to help you out. Healthcare needs to be more human, even if that means making the patient sign papers to protect the doctors from getting sued due to regretful people (reason why so many procedures are rejected or not considered), I think that we all should be mature enough to think before we act but the system needs to be more open to let people at least try to live their best lives, not everyone is going to regret getting X or Y procedure done, and those who have regretted it shouldn't make it so nobody has the chance to feel better.

(Sorry for "rambling", I grew up in the field and it's my greatest wish that people like you have the rights they deserve).