Just think, you're hating yourself. Look at all those third world countries who WISH to have a life like yours, be grateful for what you have.
The only reason you're like this is because you have a negative mind set, period. You've most likely grown up around people who've tried bringing you down or call you names and make fun of you. THOSE people, have drilled that into you head, and made you think what they say. You need to have a positive mind set: stay around those who truly make you smile (I'm sure you have 1 person) if you don't, don't go to anyone cuz I'm sure you'd rather have no one than someone who is fake a pick on you and call you names and make you hate yourself even more.
You may have depression because all your worries are in your head, from those people as I have said. Try going to a doctor and if it is serious, they may provide you with antidepressants which will help.
I, myself, have a similar situation to you and its all because of a negative mind set from those who make you feel bad about yourself and hate yourself. I totally understand your pain (I'm 15 btw) and those people, have caused me to self harm in the past and right now, I am suffering from a mental illness, called Bulimia. Try staying around positive people who bring you up instead of put you down. If you're in school like me, ask your parents if you can move school maybe, a fresh start right?
I hope I helped, it makes me sad to see people like this even though I myself have similar problems t you ! Stay STRONG :') Love x