Hi, I Had Taken Gynaset Medicine For 3 Days From

Hi, I had taken gynaset medicine for 3 days from a pharmacist to delay period,one tablet a day. My period was due on 22 feb and i took med on same day till 24 feb.I had my last period on 24th Jan and had sex with my bf on 31st Jan. Now I did not have my period started even when i hv stopped the medicine.. What could be the reason??