Can being stressed really delay your period?

I had sex 8 days ago and I am waiting for my period. We used a condom that did not break and we used it the whole time. I am 16 and it was my first time so I am really starting to freak out. I keep looking to see if i got my period but I haven't yet. I've heard that stress can make your period come late. Is that true because I don't think I'm going to be relaxed until I get it.I also don't know when I can take a pregnancy test at the earliest. Please Help Me!