Anytime you have sexual intercourse without using contraception, it increases your chances of getting pregnant. It is possible however, that your period is just late. You can take a home pregnancy test. They generally are accurate if you've missed your period.
If it is negative, and you don't get your period, you may want to schedule a visit with your doctor to ensure everything is how it should be.
For more information, please review these articles: Answers for Women: Am I Pregnant After Unprotected Sex?, and Am I Pregnant? Myths and Facts About Sex
Good luck, and let us know how you're doing.