Suggest Remedy For Delay In Periods

I TOOK ONLY 2 TABLET OF MICRONOR AND MY LAST PERIOD WAS ON FEBRUARY 21, 2011 AND I HAVE NOT SEEN MY PERIOD NOW. I TOOK PREGNANCY TEST LAST WEEK IT WAS NEGATIVE AND MY PERIOD IS NOT HERE. i AM CRAMPING LIKE MY PERIOD BUT IT IS NOT COMING. SHOULD I RETEST TODAY. 3-24-11. 1MONTH AND 3 DAYS