I Am Taking Doxycycline Twice A Day (once In The

I am taking doxycycline twice a day (once in the morning and once at night) along with taking Tri-Sprintec regularly for birth control (around 6:00pm every day). My boyfriend and I had sex without a condom 5 times this month but he pulled out every time, although we had a close call twice. I am concerned because I heard that antibiotics can affect oral contraceptives, but I'm not sure as to what degree it can mess with the birth control. Should I be worried about pregnancy?