I had unprotected sex on August 23, 2012. My period was due September 6, 2012 but it didn't come until September 22, 2012 and it only lasted 3 days. It wasn't light, but it wasn't super heavy either. I've been very exhausted and I've had mood swings and loss of appetite/nausea. Also frequent urination and cramping in lower abdomen/lower back. Is it possible I'm pregnant?