unprotected sex..missing my second peirod

i had sex with my boy friend with out protection and got my period the next day.But now its time to have my period again but it has not apeared yet after bout 4 days late..im scared that i might be pregnant but can your period change its cycle a bit after your first time of sex??

The only thing I can say is go out and buy a pregnancy test. They cost anywhere from $5-$15. Have you had any sex after that other time whether it was unprotected or not? Yes, some things can change a girls cycle. Stress, lack of sleep, exercise, medication. But I'd still advise you to take a home pregnancy test. Good luck. Remember you have a few choices if it turns out you are pregnant.