Ok, usually my period comes around the 20th or 1 or two days early. Now today i woke up today and i had my period! There is no way i am pregnant so there is no way i had a miscarriage. Why did it do this? This is about my 8th or so period i would say. I am 15 and even since my first period, it has always come around the same time, 20th. Oh, and i have never had cramps or soreness, and i still don't.