What Causes A Delayed Period After Sexual Intercourse?

after 4 days of completion of my periods..i had sex with my bf..we had taken proper protection but during sex some kind of transparent fluid came out of his body..thenafter we did not had sex.. after some days when it was time for my ovulation,it ocurred..but now when it is time for my periods to start they have not yet started yet..please advise..what could be the reason for this delay in periods..reply soon