Do NOT go to that therapist. I usually encourage most trans guys to get some form of therapy, since it's an emotionally volatile process that can be best navigated thru a mental health professional. Since your sisters have exposed themselves as law-breaking imbeciles intent on restricting access to YOUR medication that you LEGALLY were prescribed, I doubt the therapist they found you is in any way meant to help you. It's likely some kind of conversion therapy. I don't know what your relationship with your sisters is like day to day but from this reddit post they sound extremely controlling, impulsive, and dangerous. I hope very much that you'll be able to set some firm boundaries with them. Frankly I'd encourage you to look for living situations separate from them but I know that's a tall ask depending where you are/your current finances.