Birth control and period.

Ok so i had my daughter Dec 28th. Maybe in February i started birth control i believe it was the mini pill i took it every day on time until late last month. I had 2 periods before i stopped taking them. They were like 3 days apart and around a week of bleeding. Now im 12 days late for my period ive already taken pregnancy test and all came up negative. I have never taken birth control until then and she was my first baby so i dont know what to expect. Obviously if i dont get my period ill go to the doctor but was just wondering if any of you ladies had similar experiences?