My partner and I had unprotected sex on the 16th August, I got my period as normal on the 21st August and now its five days late and I'm always regular, I haven't had sex with him since the 16th because I've gone back to uni. I'm just getting a little worried now, can anyone tell me what might be going on? I guess it could be stress for deadlines and stuff.. I don't know. Thank you.

Have you tried a pregnancy test yet? That would be the first step. Be sure to follow the directions exactly. If negative, wait another week and if still no period, try another test.

It certainly could be the stress or just an off cycle. That the sex was 5 days before your period was due to come on makes it unlikely it is due to pregnancy, but obviously you will want to know for the peace of mind.