Period a week late?!

My boyfriend and I had sex for the first time on July 8th and we used a condom. The week after we had sex 2 more times and also used condoms. We tested to make sure there were no holes in the condom by filling it up with water when we were done. My period was supposed to come on the 16th but it's already been a week and it's not here. I can't be pregnant cuz he never came in me or got cum anywhere near my vagina. Are there any other reasons as to why my period is late? I'm super worried :^(