I have an irregular period. if i got my period for seven days the day after sex, could i still be pregnant?

Unlikely: Nothing is 100% when it comes to pregnancy but if you had a normal period one day after having unprotected intercourse, it is unlikely that you will get pregnant. If in a few weeks you have any symptoms of pregnancy, or if you don't get your next period four weeks after last period, do a pregnancy test. Unfortunately, having irregular periods mean that you can ovulate at any time. Use protection!