I Had Iud Removed After Four Years. Immediately Started Bc

I had Iud removed after four years. Immediately started Bc pills. I was put on antibiotics and had breakthrough bleeding on the first Bc pills. My Dr changed Bc pills to Nortrel. I was directed to stop taking first Bc pills and start Nortrel. I took Nortrel 21 days straight at different times of the day. But no missed pills. My partner and I never used a barrier method. I haven't took Bc in seven days but still no period. What should I do?