PMS, Depression, or something else?

yhcbl

My period should not be for another 2 and a half weeks. i have extreme irritation with many things, and sometimes have bouts of sadness where I want to cry. I, myself, believe that I am sometimes depressed because I have long periods of time where I feel sad and am not motivated to do anything. I'm also very irritated during that time too. I can't tell if what I'm experiencing is PMS or depression...There's no sadness associated this time...so what's up? Anyone know? I'm 16, and I started my period when I was 11....and it is a regular period.