I've been on birth control for about three years now. And I was switched to Tri-Sprintec a while back, and I've never had any problems. But recently my period is two weeks late. I stopped taking them last month because I got too behind. I had unprotected sex during this time, but he did not come inside of me, and I took a pregnancy test and the results are negative. I was just wondering if this could be a side-effect of me not taking my pills?