I took plan b used correctly,three times over a course of 20 days, i am supposed to start my period this week. should i be worried if i do not get it?

Check preg test: Probably okay, but should check pregnancy test to be sure

Plan B may: effect timing. Potential side effects w emergency contraception include menstrual flow changes (spotting, bleeding, early or late period). If you miss your period -take a home pregnancy test. If your period appears to be seven or more days late - consult with your gynecologist.