Plan B pill and birth control

Patient: I have taken the morning after pill and my period has been delayed for 3 days now. I took a test and I tested negative I know I took it soon according to my packet I should be starting my birth control pills in one more day. Yet i havent had my period. I had unprotected sex, but he had not ejauculated, and on top of that I was religiously taking birth control pills for almost half a year now. this month I had maybe missed 2 but doubled up the next day. When we had sex I was on my last pill the day before to start my period. So the day after we were intimate I had taken a morning after pill just as a precaution. Yet I’m still worried. Im in need of advice about how late a period is after taking the morning after pill and what should I do about my coming up packet of BC. Please help!

Symptoms: None

Doctor: