I Had Unprotected Sex..i Was Fertile At That Time..we Only

i had unprotected sex..i was fertile at that time..we only use withdrawal but i was not sure if no sperm has been ejected on me ..i take 4 pills of nordette 6 hours after the incident..but the other 4 pills which supposed to be taken afer 12 hours after the 1st dosr was delayed for about 5 hours because i fall asleep.is the pill still effective?.thank u