Are you "out" at school (even if not definitively stating you are trans, but even just presenting as non conforming) or is this something you want to keep very private? I think the dynamic may change a bit.
Regardless, if you have a good counselor, I feel like that addressing the issue with them first might be a good step, particularly if you want to keep things quiet since they are bound by greater confidentiality whereas teachers are not. They may also in general be able to act as an advocate. Assuming of course you have a good one at your school.