I have been taking Tri-Sprintec, which is a generic version of ortho tri cyclen, for about a year and a half now. I have never had a late period or even missed one since I have been taking it. This month my period was suppose to start a little over a week ago and still has yet to come. My boyfriend and I have been sexually active for a while, we use condoms and until last night we have not had sex in just about a week. I am really worried and concerned. Is there any way you could possibly explain what might be going on?