I am on birth control, and am on my withdrawal week. (Not sure the exact terminology, but we shall go with that). I haven't had sex since my last period, so I'm sure I'm not pregnant. I'm supposed to start my new pack tomorrow evening. Usually I get my period before now. I haven't been as stressed as I have been the last couple of months., although there has been some financial issues. Should I be worried if I don't get my period?