Pupu,
have you been diagnosed professionally with depression?
I can relate to what you are saying, though I am 26 and am only now really trying to tackle this so that I don't spend another day feeling like i'm not "applying" myself to life.
I was diagnosed at 14, though it was never treated or taken seriously by my parents- I guess a forced smile was supposed to fix everything.
The fact that you are here posting your feelings and situation shows that you are willing to look within and make changes. That is a great step.
I am not the biggest fan of talking to a Dr. Right away. I would try to find a counselor or psychotherapist (1st choice) whom you feel comfortable with and you feel is really listening. Talk about what you are feeling and the ins and outs of your history. Ask many questions about meds and alternative therapies. Exercise, diet, and activity (even if its just walk) are great ways to get past the initial dpresssion and are immensely important in every day life for anyone anyway.
let me know what you find out...Or if you just want to chat.
Taopaz