-Have you spoken to your parents?
-To school administrators about any accommodations you might need?
-Have you talked to your therapist?
-Do your friends know?
In other words, have you laid the groundwork?
As for an outfit, just get something that will fit in with the other girls at your school. There isn't really much need to go out and buy a pink tutu to show your transformation. Makeup-always remember that a little makeup to accentuate your beauty is good, but there is no need to wear ALL of it.
Shoes-again, wear what the other girls wear.
