I know it's not likely but..what's the odds?

Ok ladies, I need some help! My hubby and I are ttc baby #3. Last month my hubby left for work for a month. We had sex before he left (Aug. 15) and my period was supposed to come on Aug. 18th. It didn't come until Aug. 21st. It wasn't as heavy as normal but it lasted 5 days. I obviously didnt have sex while he was gone, so here's my problem, I was due to start my period sept 8th. It still hasn't came. Is there any possibility I could be pregnant? I know it's highly unlikely..but thought I'd ask. I've had a few symptoms, but I know they could very well be period symptoms.