I'm not 100% sure when this started, but I just remember getting my period the end of May and knowing what to expect so i would guess a few months before May... I am 22 my periods have always been normal, even after i had my daughter 3 years ago. But recently my periods get extremely light the 3rd day into my period then goes back to normal days 5-7. I'm not too worried about it just curious if its normal. Seems as though each month I have different pms symptoms which is also a little weird to me. If anybody has any helpful hints as to what is could be causing it, if anything at all.
Stress may trigger early periods, as well as many other factors.