please help me. pregnant?

Please please help me. I'm so scared. 
I had sex for the first time 6 days ago (on the 18th) and then again on the 20th. I was expecting my period on the 20th. It is now the 24th and I have not gotten my period. We used a condom, I am not on any other form of birth control. As far as both of us know, nothing went wrong? Should I be worried that I'm pregnant? I know it's too soon to know, and I will test in about 5 days, but am i worrying over nothing?