I do not have a regular period and have not had a regular cycle since my period started. I have talked to my dr about this and he assures me that everything is fine. My question is, how do I know when to take a pregnancy test after birth control failure (broken condom) if I don't know when I would technically be missing my period. I did have my period last month from the 11-16 but before that I probably had a period in january or february.