<Light TMI> I have no idea what's wrong with me..

Ok, so last weekend Saturday October 3rd, my SO and I had sex and he came in me for the first time. Then again Sunday 4th, Monday 5th, Wednesday 7th and again Thursday 8th. My last period was September 17th and I'm supposed to have my period next week Thursday October 15th. This evening I was totally fine, then the last hour I got Super emotional and went through getting annoyed, happy, sad, and I started crying, all over nothing. I have no idea what's wrong with me.. Could I be pregnant? Advice anyone??