Hii doctor.. I had unprotected sex with my girl friend on 15 of march..after that she took I pill with in 12 hr.. Now she missed her period.. Her actual date of period was 9 of April and 9 of may but till now haven t any symptoms of period.. We done urine hcg test various time after missing a first period it s coming negative.. What is the cause of late period?? Have any worried about it?? Is any chance of pregnancy??