Hi, My Last Period Was On July 13 Lasted Until

hi, my last period was on july 13 lasted until july 19. we have the deed on august 4 accidentally he cum inside. i took nordette on the same date at 10pm 4pills and another 4pills on august 5 at 10am. my concern is i haven't have withdrawal bleeding yet. it's been 7days now. can my period delay? is there any chance that i will be pregnant even if i took nordette immediately? im so paranoid please help.