I had a sex with my bf 4 days before my period.he did not put his penis completely(just 1/2 inch went inside).after 28 hrs i took plan b one step contraceptive pill.my regular period is on jun 20th.but i did not get it till now.i am not even getting any stomach pains like periods.I am so scared.is it common getting periods late after taking plan-b one step.or am i pregnant.please answer me as soon a possible.