Am i depressed? Please help?

i'm 14 and i'm really confused. Over the past few months I've been withdrawing from my friends and family. I cry often for no reason and have repeatedly thought about self harm and suicide, though I've never done anything about it. I always feel at least partially upset about something, even if its small. One of my teachers has noticed and asked about it but i was too scared to get help. I don't know what to do. Thanks for any help.