can unprotected sex delay your period or change your cycle?

okay me and my boyfriend had unprotected sex and he pulled out on time juss before he came. its almost the end of the month and im just wondering why i havnt gotten my period. i kno im suppose to get it this month but it feels like its taking forever. i got nervous and took a pregnacy test which came out negative. im thinking about taking another just be sure but i feel as though its going to come out negative again. i have no early pregnancy symptoms and everytime i poke or punch my my stomach it is soft as ever. i wanted to kno if unprotected sex can change or delay my period