Clinical depression, plain normal temporary sadness, or just hormones? What's with me?

I don't have suicidal thoughts, nor do I self-harm, though I've done those in the past. My sleeping routine's out of whack, completely irregular, e.g. sleeping 13 hours one day and pulling an all-nighter the next day, My appetite's been the same? I don't know. I seldom feel happy, but yeah I do smile and laugh randomly, though not with very much feeling and not for more than 1 minute even. I cry most nights. Not all, but most. I used to be quite happy when I went out with friends but not anymore even. My friends all comment on how listless I look and how quiet I am. Doesn't help that I used to be quite loud. I feel tired, very tired, beyond measure all the time. And no zest for life, can't find much point in living but everyday goes by just like that. Feels like I'm kinda pressed for time with it going by faster than I notice but I don't think of suicide or self-harm though I used to. I get agitated and moody easily like by just reading a friend's blog or a tv show but I never really cry any tears out till I get to my room. No one really knows about me being like this. I just feel numb, dead in some way, physically alive but dead in all humane ways. I won't even say I feel much emotion. Problems and things that used to bother me don't seem to matter anymore. Basically my system's gone mad. I'm 13, if that helps. And I don't know what made me this way so yeah. Sorry about this being so long. Yeah I think it's been more than 2 weeks. But I don't know if it's just me subconciously making myself this way or not, just feels that way a little. Help?