Hi, Whenever you start taking oral contraception, please do remember that the initial couple of cycles are not well protected and additional means of contraception is needed. If you had a period during the first week of August and failed to see another one in September, there is still a possibility of failure though you did not miss any pills. In the current scenario, the best thing to do is to take a blood test for pregnancy and see a specialist for further evaluation. A sonogram of the pelvis, preferably in the trans-vaginal route also helps. Take care.