I take tri sprentec birth control pills and my cycle usually last around 22-23 days. I missed a few pills during my last pack, but started at an expected date of May 10th. The last week of my pack I know for sure I missed 2 pills. My boyfriend and I had unprotected sex May 9th and he came in me. How likely would I be to get pregnant the day before my period? When will I know? I didn't restart a new birth control pack because I didn't have one at the time I usually start it.