Miss period and unprotected sex.

Hi sir/ madam I had unprotected pull out sex with boyfriend at 24 February but there is lesser chance that semen got into vagina but now symptom shows like miss period. My last period duration is 13 feb-17feb but as i take pills to regulate my period it has no effect i take pills 5-6 days before it feels like i am pregnant. But i also have miss period problem due my overweight issue  i consult doctors for this he said you have to loss weight but i can't my last period came due to medicines given by doctor.my weight is now 88 kg age 20 so can you clarify me is this pregnency or any diseases?? When in December I have miss period problem doctor suggested me to lose weight and take pill norethisterone tablet gynaset for regular period. My mother also have miss period problem may it could be genetic problem or pregnancy???