Hi there, I have understood your concern. . I will suggest you the best possible treatment options.
1 ) First of all do not panic.
2 ) If you have taken the birth control pills regularly, and your unprotected sex act was at the end of active pill days then you need not worry about the
pregnancy.
As the pills have already suppressed the egg formation and you have already taken the missed pill , please don't worry.
3. Also,
emergency contraceptive pill taken within 72 hours of unprotected sex act helps to prevent the pregnancy in 95 % cases.
4. Now , I will suggest you to simply wait for the onset of the cycle.
With emergency contraceptive pill, withdrawal bleeding can be eratic, it can be Scanty or heavy and it can early or late.
I hope this answer helps you.
Thanks.
Dr. Purushottam Neurgaonkar