I Am 22 Year Old.my Weight Is 65. I Am

i am 22 year old.my weight is 65. i am on ginette 35 from past month .my doctor prescribed me for acne treatment.he prescribed me to start from 5th day of the periods. i completed 21 days cycle also he suggested to again start on 5th day of period . during this duration i had unprotected sex. i had 7 medicine free days still i haven't got my periods? am i pregnant and what are my chances of getting pregnant. i had the medicine regularly n timely.i read it acts as oral contraceptive.