pregnant??

i had sex for the first time about two weeks ago and my period was supposed to come yesterday but it didn’t? i guess my cycle does vary by a few days every month but i’m scared i might be pregnant? am i just worrying for no reason or should i go buy a pregnancy test? i do feel PMS-y so here’s hoping, but this has got me so stressed out! i want to add that we used a condom and it didn’t break or anything like that, everything seemed.. contained. i am not on birth control though. help!