Hey Lucas!
I'd think about maybe getting the support of a therapist.
I am glad you sister supports you; yet, I also wish she would not out you.
I'd also keep an eye out for support groups.
I am glad you know that binding all of the time can do damage. I'd wanted to make sure you knew this.
Some young people get so desperate about their transition that they run away from home. I have known a few. It does not go well at all. Please do not run away. It's just not safe. You will have a better life if you stay with your parents and get support until your parents change their minds or until you are 18 y.o.
Right now is a good time to also stay focused on your education. Education/training all add up to earning power and, ultimately, to having a better life even after your transition.
The bottom line is: You'll want a good life! So whatever you do, take really good care of yourself!
You deserve as much support as you can get. So, maybe focus on ways/places to get healthy support?
You have my support.

WC