I can really identify with how you feel right now. You know what you need yet are being treated like a fanciful child, pushed into a category that just isn't you.
I recall, when I was younger having my feelings demeaned as teenage rebellion. 'You'll think differently in 20 years', they would say. I did. 20 years later I was miserable and thinking back on what a lousey 20 years I'd just had. (Though I can't really blame others for all of that).
It seem to me you have three choices.
You could simply go along with your mother. Dress as she says, act as she says, look forward to a life of medoricrity, trying to please some man and win the approval of society. Getting your kicks from the flag and the latest politician in the political beauty contest. (Women like that are usually called Republicans).
You could stand up for yourself, sneeking behind bushes to put on a binder, being continually dismissed as a rebellious teenager and a problem. Like all negative labels that will stick of course.
Or you could try a more gradual approach.
Accepting that boobs don't mean anything that you don't want them to. You can deal with them later. For now, you need to deal with how people treat you.
Start by telling that teacher. Then your friends. But you really need to get one thing sorted in your mind, your sexuality. If you make this a sexual issue then you will simply attract sexual attention, or worse, not.
The point is, what your mother is actually saying is that she wants you to be a normal teenage girl, meeting boys, never having sex, (of course), then bringing some nice boy hom, marryiing him and so on. Those around you will tend toward seeing you either as a potential for conquest or a competitor for the best ones.
If your need to transision becomes a sexual issue, it will be treated as a tactic to attract boys. Whatever your sexual preferences are, your needs are about life and life isn't about sex.