Had unprotected sex a week before my period. i am irregular and i started my period yesterday. is there still a chance i'm pregnant?

Not at the same time: A woman cannot get her normal regular period and be pregnant at the same time. However, she can get pregnant a week or two after her normal period. If she has some spotting or light bleeding that doesn't look like her normal regular period, she can check a urine pregnancy test about 3 weeks after sex (when conception might have happened) to see if she is pregnant.