It sounds like regular period pain. The only way to tell you are pregnant is to take a test either the one you buy at the pharmacy or the one the doctor administers (Blood Work, Urine Sample). My period was not completely regulated only 3 months in. And it's always suggested you use another form of birth control for 3 months in to the pill because it has to get in your system effectively. Which is why you need to start it before you even become sexually active to ensure it's success.