I would still recommend the normal way of doing things, going into therapy and taking the medical route. But there are ways. Discussing them might be accompanied with heavy skepticism and disbelief, but I can hold the same cynicism and begrudge organized religions, but both are against forum rules. So here is what I have to say when it comes down to freedom of thought and expression considering your question philosophically:
In magic there are indeed ways to transform. It isn't easy, in fact it may require years of practice. One of the best ways to learn transformation is the emulation of animals. Pick an animal that has the required gift you seek, and study the animal. Learn it's secrets by observing it. You could learn from a fox. A fox can teach you stealth and invisibility. The fox is a master of stealth. By observing it's behavior, you can master it skill and even obtain it. Lots of cultures worshiped animals in order to gain their skills and magic. Most oriental martial arts is based upon emulating animals, their strength and their behavior are routinely integrated in the practice of martial arts. So it has some merit, to the degree your imagination allows it to be.
Not to be confused with
Species Dysphoria 
A more practical way:
You could start in working on your inner life. Do you agree that people will judge you on how you express yourself? when you are sad, are people treating you differently? or when happy? So how you think affects reality. It is all about changing the inner world, and project it unto the outer world.
At one time I was so fearful about to get clocked as trans, and indeed the fear of being clocked was enough for someone to clock me. Ask any trans, they all agree that "confidence" is the most important factor in passing. Why is that? because you create reality. When you are certain you are male or female, then this will show through projecting confidence that you are. Your mind is controlling matter by just thinking. Think confident, and you are. It is that simple!
You could perform some spells for yourself. Don't buy anything, it's mostly rubbish anyway.
Before going to bed, tell yourself what you want. Do you want less breasts? ask your subconscious to let it shrink. Say to yourself: no one will notice it, and repeat it before falling asleep. This is one way of training your mind and it is basically a spell for change.
Then when you are ready, someday it might also be surgically removed. In the mean time, you could train the mind to already believe that it shrinks or goes down. When you do, people will pick up on it.
I wish you good luck!
