Hello, and I hope I can help you today. First of all, I want to reassure you that if you have been taking your birth control pills as directed and you didn t miss any that the chances of your being pregnant are extremely small. The failure rate of birth control pills in general is about 1 in 200 per year, meaning one out of 200 women has a chance of getting pregnant on the pill over the course of a year. Many women can miss periods for reasons not due to pregnancy. Your period can be affected by diet, traveling or changes in your schedule, and especially stress. Even worrying about pregnancy can cause enough stress to delay your cycle. Also, some women stop menstruating completely when they have been on the pill for a long time, especially low-dose pills like the Microgynon you are taking. I suggest you purchase a urine pregnancy test (the over-the-counter ones are just as accurate as a doctors office) and follow the package directions. If you are not pregnant, you can just wait and see what happens with your cycle and even if you never bleed just start your new pack on time and you will be protected against pregnancy. If your irregular periods continue to bother you, you may want to see your GYN provider who may be able to prescribe a different pill for you that may help you have predictable cycles. I hope I was able to adequately answer your question today and that my advice was helpful. Best wishes, Dr. Brown