I started Tri-Sprintec the sunday after my period. I had been using it for 5 days when I had unprotected sex with my boyfriend and he ejaculated in me. This happened not even a week ago. I found out recently that it takes 4 months for birth control to fully work. But I've also heard that it only takes one week. So, how long does Tri-Sprintec take to actually work? (My doctor didn't say anything about it when he prescribed it to me, and I have tried, but I haven't found an answer anywhere.) And my second question is, do I have a chance of being pregnant? I was ovulating when I had unprotected sex.