My last period started May 10th and lasted 5 day. On May16th I had unprotected sex and took the morning after pill on May 17th. one week later May 27th i had another period and it lasted 4 days. it is now June 23 and my period has not started. my body does not feel any different from normal Im not tired or having any symptoms of being pregnant to confirm i took 3 pregnancy test all weeks apart and all 3 are negative! Does Next choice or Plan B cause a significant delay for a menstrual cycle?