my last period was july 18th. my cycle is 5 weeks.. so about 35 days i guess. and my period usually lasts about 5 days. i had sex from august 1-16th while i was visiting my boyfriend for 2 weeks (he lives in another state). about a week later i made a mistake and hooked up with an ex. im 99% sure its my boyfriends. but i just need to be sure.