I am 23 year old........i have sex with my boyfrnd 18 days earlier (after 1 week of last menstruation).......he had used condom and after sex i have seen the sperm inside the condom........if i am sure then it doesn't break.........but today the 28th day is complete of my last menstruation............no sign of blood still now...........i am taking medicine for gall bladder problem........but i have not taken any pills till now.............what to do.........plz.....plz help me.........