My period started on Saturday, the 21st of July after my boyfriend and i had sex on the 20th, protected, twice. Nothing broke, that i know of. Today, it's light bleeding and looking like it's about to end. That's like 4-5 days, instead of the usual 6-7. Is that normal? Can sex make your periods irregular in ways? Like shorten, elongate, make them heavier, lighter, etc. My period also came earlier, on the 21st instead of the 25th, 26th or 27th. But i live with just my mom and her period came early this month, so sometimes they say you and the female you live with can have same period cycles. Is that what it is? I'm not pregnant or anything like that, am i? Since i still got my period? I also used a tampon yesterday when i normally use pads. I don't know if that had anything to do with the matter. But my period's been short before, i think. I have a bad memory unfortunately. So please, any help fast with understanding this would be great. Thank you.