... my period yet! I have been on tri sprintec for 6 months and have always gotten it on the 3rd day. I had sex once this month, but we used a condom and I am 99% sure that didn't break. I haven't missed a pill either and I take it in the morning every day. Can having sex alter the day that I start? Or maybe stress can alter it? I am freaking out. I just don't think that I can be pregnant when I have been faithful to the pill and used other forms of protection! Maybe I'll start on the 4th pill this month? I don't know. Has this ever happened to anyone else before? I've heard of missing periods on the pill and not being pregnant, but I don't know about tri-sprintec?