Seeing signs of pregnancy, help?

About a month ago, me and my boyfriend had sex.. one time it was unprotected and even though he pulled out he still came on me and somewhat in me. About three days ago, I started to feel nauseous and just plain sick to my stomach during the morning and as the day would go on it would get better. I'm feeling extremely tired and bloated and I'm having these bad headaches.. I'm worried that it might just be stress or if I could possibly be pregnant. And information or suggestions on what to do would really be appreciated.

[remar]

It only takes one unprotected sex act at the right time to get pregnant. Are you late for your period yet? If so, then take a test to see if you're pregnant.