3 days late please help me

Im 26 years old and this is my first time ttc. I had unprotected sex with my fiance on October 21 and i was supposed to get my period on Monday November 5th. I am now 3 days late and experiencing minor heartburn and headaches and backaches. Ive also been nauseated and i sometimes have troubles to finish eating my meals because i feel like i want to vomit. Im also bloated and have dull aches in my lower abdomen that come and go. I have been stressed too. Could i be pregnant or is aunt flo still on its way? And when should i take a test? Please Comment what you think. Thanks