Confused😞

My period was over a week late and my cramps are really bad.. But my period is so light! Usually i wouldn't have any cramps and it would be regular bleeding but way heavier to what it is now! Usually it lasts for 5-6 days and I'm on day 3 now and I say today could be my last. Would being underweight/loss of appetite for the previous month have anything to do with it?
(Don't mean to be crude but I also bled twice just a tiny bit after sex this month)