I think I'm depressed?

I honestly think your best bet would be to see a counsellor. Wether it be through a school or go to your doctor and get a recommendation. They will prescribe you Anti-Depressants (depending on your age) and it will boost your self esteem, just until you return to normal. If your a teenager, a high percentage of others are going through the same thing, don't stress too much over it. Just see a doctor and they will help you. :)