i understand how you feel, i went to an all girl high school, a prestigious place, but i was the poor girl in the rich girl school. i would maybe tell or ask your parents if you can switch schools, they aren't all bad.you're going through puberty too which could be a reason you're depressed and tired too. i hope thats not too personal to say, but i remember how bad it was for me. your sisters are older than you too so they have had more time to get out there too. you're young and have your whole life ahead of you, maybe you might have to see a doc and t if possible.