Oh man, high school times, anxieties, girls... Been there, done that. The first thing you should know is that this general anxiety is but a small symptom of an entanglement of issues raising from just being in high school(no, being locked for four years every day in a box with a bunch of bored teenagers doesn't do too much of a good job in making you a happier person, or keeping you sane for that matter, yet for some reason we still do it) and a bunch of stuff going on in your brain, growing up and the like. I don't know you situation, or how well can you relate to anything I will say in this post, but I'll try to give you some advice based on what I wish they told me when I was your age.
A good start for getting rid of your anxeieties, worries, and so on, could be
http://www.raptitude.com/2010/02/3-pieces-of-advice-id-give-my-18-year-old-self-if-i-could/. Just give the blog a shot, read this article and two or three others, see if it makes any sense to you. The whole thing is worth reading, actually. Oh, and if you indeed admit that it indeed has something to it, don't expect all those new worldviews and habits to kick in right now, it takes time for them to latch on. The starting article I chose is a bit symbolic, I too wish that somebody offered me some real advice when I was in (high) school, instead of absentminded remarks like "Everybody's been through it, you can do it too." or "Kids can be cruel."
And finally, the advice I can give from my own experience, i.e. things I wish I knew or did when I was your age:
1. Do research about how to skip classes and then do it. Ask your parents, teachers, principal, ministry of education, google, or anybody about under what circumstances can you skip years and earn you high school diploma sooner(remember Sheldon: "It took you four years to get through high school?"). You'll probably have to do a ton of studying and practice, but your reward will be years of your life when you're out of high school, ahead of everybody else, and on a college(Be *careful*, and I mean really freakin' *careful* with the student loans, if you'll have to take them. Consult a lot of people and the internet before making a move. Remember all the game designers and english majors flipping burgers and standing behind a counter with a debt on their hands! This is a chapter by itself, read up choosing(or at all going to) a college real well.), which can actually teach you something, as opposed to high school. Which gets us to the second point:
2. Do not be scared of work. When it really comes, it's never as bad as it seems from a comfortable life situation when you don't have to do much stuff and don't have much responsibility, such as high school. More studying or more difficult courses to take always seem daunting, you'll always imagine yourself slaving away half a year only to fail at the exams and lose all that time you could have spent just chilling out or playing videogames, but it never turns out like that when you're actually doing it.
3. There aren't any untalented people, just ones who don't put time working on some of their talents, and bad experiences that teach them not to. For eaxmaple, you know why I hated and avoided math throughout my school life? It wasn't the functions and absolute values that made me want to run away every time I saw them, it was my vicious math teacher from the elementary. I could see her wrinkled face evey time I looked at an equation and hear her humiliating smartass comments(and the class' laughter) every time I made a mistake, all that wrapped in her terrible cigarette-stained breath that made flies drop. This article offers a great analogy on the relationship of talent and the work on it:
http://www.cracked.com/blog/6-harsh-truths-that-will-make-you-better-person_p1/ Look for the dirt->tomatoes part.
4. If you find yourself in one place with idiots, remove either them or yourself from there. Trying to change them or accomodate your behavior to fit in will not work and will make you miserable.
5. Do not be afraid of making changes, of doing something that's untypical for you. I know that people can be really annoying at first when they comment on some visible change and you hear the same remark 20 times a day, but that will pass. The present state of things, even if it sucks a bit, hell, even if it sucks a lot, is always more appealing, more comfortable to the usual human mind than making a change in any direction, because it's
familiar, but following these impulses throughout your life will only lead to unfulfilling careers, families you're not really part of, and ultimately, deathbed regrets.
Hope some of it helps!