Mine started just before i turned twelve and was irregular for about three years I think. It comes about every 30-32 days and is pretty regular now. I used to get excruciating cramps for 1-2 days, and sometimes vomiting. It isn't quite so bad now, but sometimes I do get bad pains.
But it's very light, though. It's hardly there at all. It doesn't come every month, esp. when I'm not on the pill. Everything between 30-50 days...and I'm 20 now.

I'll make sure I do eat more. 
