I been through it all kid, and I don't care. Here's why.
These kids know NOTHING ABOUT YOU. Why does it matter what they think? They don't know you. Even when you get older, and some jerk honks at you on the road because he doesn't like that you won't speed or some stupid crap, why should you care? The only people who can hurt me are the people I know, because they know me too, and if they say something about me...they're probably right. And if what they are saying about you IS true, then fix it.
Also, anyone who tells you that people are bullies because they have a rough life, are rarely right. Life isn't like that. Some people are just malicious. And more often, because they've had such a good life. They don't know suffering. They always got they wanted and they intend to keep it that way.
As for how you look, again, why care? You were born that way and it's nothing that can be naturally changed. Anyone who does care is simply shallow and not worth your time.
You have to stand up and be proud of yourself. You have to show people that you have no fear. The world is a gruesome place, and most people aren't good natured. Nobody is a perfect person, and the people that seem great right now will probably live terrible lives when they are out of high school.I know people who used to hound me that already have kids, some who are stoned 24/7, and others who are in jail. And I don't look at it as revenge, I really pity them. They were born into a society that defends and encourages this behavior. In the end, it's not their fault, and I have nothing left but to forgive them.
And if you want to encourage that behavior, you have to forgive to. Don't hate anyone who ever picks on you or puts you down, or whatever else. The future is uncertain, and for people like me, ends at death. There are likely no second chances. Forgive and forget.