i am supposed to have my period last dec 17, and i had unprotected sex on dec 18 because i was expecting dat my period is coming so i think its safe..i took pregnancy test the morning of dec 18 and it came negative,,.and its already dec 20 now, and i took pregnancy test again and it came out negative..im worried coz my period is regular..and im almost 4 days delayed now..plz anyone help me what would be the best thing to do ..is it possible that im pregnant????