missed period 2 months in a row, please explain!!

okay so, i’m 17, i’m on the pill, i take lo loestrin and i take it regularly, same time every day. i had sex march 17, on the last day of my period, and since then, i’ve missed both my periods. the guy i had sex with said there was just precum when we did it. i don’t think i am pregnant but missing my period is very irregular. i’ve only seen 2-3 days of very very light spotting. that’s it. i have no pregnancy symptoms or sickness or anything like that. i don’t know what’s making me miss my period. i’ve been on the pill for a little over a year now and i’ve always gotten my period on time since then, but haven’t had it for the last 2 months. can someone explain???