I had a protected sex 2 days after my period as my period of july was started on 25th july and it finishes on 28 or 29 and i had sex on 31 july according to 28 days cycle this time i should have period on 21 august but till today (30/8/2013) i have no period and also checkd through the home kit the answer was negative i checked 2 time firts on 25th july then on 27 but the result was negative.I never missed my period but this time i missed it. plss suggest me what to do m really very tensed?