Thank you for your question, and for joining EmpowHER. Anytime you have sexual intercourse without using contraception, it increases your chances of getting pregnant. It is possible however, that the cramping is just normal PMS symptoms. If you don't get your period when you expect it, you can take a home pregnancy test. They generally are not accurate until that time. In the future you may want to practice safe sex using condoms, withdrawal method, birth control pills, spermicide, or whichever methods work for you and your partner (pick 2 for extra protection!) to safeguard against unwanted pregnancy and STD/STIs.
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.