You're 15. Any "high school relationship" you have now probably won't last too long anyway.
Besides, there's heaps of time to make friends and get relationships when you finish school and go off to college and/or get a job. By that time you will have a car, you will have more freedom and you will be able to spend more time with your friends.
At your age, I was exactly the same way. I never went out much, nor saw many people outside of school and I wasn't exactly the best with the ladies. But most of that got remedied in the last year or two because I got my license, got a job with people around my own age (I took a girl I worked with to the school formal - or "Prom" as you call it there). I think social skills are learnt in due time, it's just unfortunate some people don't have the resources at a time when they need to be social to fit in.
Hang in there, it'll get a whole lot better. Trust me.
