Do I Have A Purpose

Questioning and wondering every day whether my purpose is to exist or live, this world has got me down and out. I feel one way one day and another the next. My question is why do we feel so many emotions, especially as teenagers, that cause doubt and conflict within ourselves? Why do we make ourselves suffer when we don't need to? I only have that one question, because it seems to be universal, to not just me, but to all the teens that are surrounding me. We seem to beat ourselves up over something so simple, and then expect people to feel sorry for us when it's all said and done. Any insight? I'm willing to take it from everywhere.