Physical & Emotional Abuse Support Group
Abuse is a general term for the treatment of someone that causes some kind of harm (to the abused person, to the abusers themselves, or to someone else) that is unlawful or wrongful. No one deserves abuse, period. Abuse can be emotional, physical, or sexual.

Is there any adult that you trust enough to share this with who might be able to help you find some resources in your area?
Something else you can do to prepare for turning legal age is to make a plan to get out as soon as you can. If you don't already have one, get a part time job and save your money. Study hard and do well in school. Do some volunteering. Some employers still pay attention to these things. If you plan on going to college, research financial aid resources that include housing. When having to live in a toxic environment, you might have to do that research at the library instead of at home.
I hope you are able to find some resources, including a qualified therapist. You might start by calling the suicide hotline https://suicidepreventionlifeline.org/ DV hotline. http://www.thehotline.org/ to find some resources in your local area. (these are just two of many links to various helpline sites) You might also research national groups that support various genders to see what resources may be close to you.
One thing you can do is to come up with some positive affirmations to say to yourself when the toxic ppl in your life are putting you down. For example, if they call you stupid. You can silently say to yourself, I am smart. When they say you are helpless, you say silently to yourself, I am powerful. When they say you are worthless, you say silently to yourself, I am worthy and deserving of unconditional love. Our brains cannot handle two opposing thoughts at the same time. So just keep saying those affirmations (and any positive ones you come up with) to yourself all the time. It really helps to look in the mirror, directly into your own eyes, while saying them. (Don't be surprised if you start tearing up. That's normal.) Oh, and one more positive affirmation. I am perfect, just the way I am!
~healing hugs~