Hey,
I'm sorry it's difficult for you and that your parents aren't entirely supportive. Have you tried sitting them down for a good long talk? I could imagine they're in denial somehow, pretending this will go away. Especially if you mentioned to them yourself it might be a phase.

Also, do you have access to counseling? This could be helpful for you but it could also help assuring your parents that you're not "rushing" into anything and are very sure about transitioning.