You wrote a long story, its good, talking about your problems sometimes makes you relief.

Some small part of your story that reminds me of myself when i was 17
"it turns out a couple of them were just using me. I've always been socially anxious. I'm very shy. I don't know if I have Social Anxiety Disorder, because once I know people, I'm very comfortable around them. However, in a room of unfamiliar people, I get very on-edge, like people are watching me or judging me... but being with someone I know makes this less stressful. My feelings of "paranoia"?
It feels like everyone in the world is having a good time around me. I don't have any friends, really... I'm paranoid, so I can't leave the house. It feels like I can't move forward
17. No girlfriend, ever. A virgin. Never been kissed"

I remember i'm starting to feel weird about myself since i was 17-18. I started to feel depressed, suicidal, or want to kill someone. But as a teenager, i dont really understand about my feelings at that time, confused, so i'm not trying to seek any professional help, and its getting worse now. Maybe yes you can try to find some help, worth to try, from your family or outside family. You sounds like me, maybe, i dont know. What you wrote up there, is exactly the same like me.
Just thought i'd share a little similar story of my life.

About the advice that you're looking for, i'm not really good about giving advice, but the school years is a hard time for people like us. Friends, romance, self-confidence, etc. You will get through whatever happens ahead, its just a matter of time and how you will get through it. It could be a good way, or bad way. Maybe i can only say, dont let people control you, you have to stand up in front of your friends, dont let them use you. Socially anxious? I am still today. But maybe from now on you can try to control your anxious, build your self-confidence, as you grow up perhaps you will get better and better person. Everything can starts from teenage years, whether it's good or bad thing. Try to always think positive.

Sorry if you dont get your answers from me, or the advice that you're looking for. But reading your story, makes me remember my awful teenage years, i just want to share a little of my story.

And, i had my first kiss when i was 19. I never had a girlfriend in highschool because i'm a loser, loner, quite, dont have many friends, too afraid about everything.

I'm a very depressed man today, its because i cant control my feelings since teenager, maybe if i can control it i wouldn't be this kind of person today. Or maybe, i was meant to be like this. You're still young, well i'm still young too, 29, but while you're still 17, try to live happy, and hopefuly you will become a happy person in the future.