The pill works with efficacy if taken within the stipulated time interval and the sooner it is taken, the better. It is common for breakthrough bleeding
to occur after the use of the pill as it contains excess of hormone that disturbs the normal balance of the body. It is also possible that your period may be disturbed for this cycle at least. If you do not get a period within 10 days of your expected, you should see a doctor for further management . Good luck.