Am I depressed, I don't know, help?

If, as you said, your brother is really good-looking, then it's not that he got all the good genes and you got the bad ones. You and him develop at a different rate. One day you'll be very good-looking. Tell your mom everything you told us. It's common to take things out on your parents (I do that all the time and then feel like sh*t for it later). Give a sincere apology to them if you've done anything mean lately. I really believe you'll be pretty later on. For now, try to find nice makeup to wear, find and enhance the things you do like, and wear flattering clothing to make you feel better about your appearance. Try to talk to a counselor at school to see what they think about it. They'll know if you need some professional help.