hi, I have been having regular menstrual period for as long as i remember, but since 3 months ago, it came in almost two weeks late and the flow was very minimal, it almost took more than one week, unlike during my regular menstrual period before which only last to 3-4 days. Then this month, still came in late of more than two weeks before i had a flow and it it is so scarce and since then I have been having these minimal flows for almost 3 weeks now. What could this be?