It's unlikely that she will be pregnant. However unprotected sex do leave in some sperms inside. The menses are delayed because of the overuse if the unwanted 72. It has harmones that have direct effect on ur menstrual cycle. Wait few days for the menses. If it is delayed beyond 7 days of your regular menses then do a urine pregnancy test just for safety.
Ps: the menses for the next 2 cycles might be irregular. Do visit a gynecologist if it stays irregular.