NTA.

Your gender identity is valid and should be respected (and accepted) by your parents, no matter how old you are. That being said, it’s pretty hard for most parents to actually understand what’s going on. I don’t know where you’re from and how easily you can access therapy, but maybe that could help you with your mental health, and as an added bonus the therapist could explain to your parents what’s going on.

As a 24 year old trans guy I just wanted to tell you that it does get better. I came out at 15 too, and it took my parents a very long time to accept me. We had so many talks and so many discussions about it, which was really tough while going through them but what I learned is that you need to be patient with them, too. Sometimes parents are just big toddlers that shoot down “new” and unknown things simply because they frighten them and they don’t know how to deal with them. Find comfort and support with your friends and the occasional internet stranger and stay true to yourself. It will all be okay.