Good After Noon My Last Mental Cycle Was 10/13/2015 From

Good after noon my last mental cycle was 10/13/2015 from how I have tracked my ovulation I should have ovulated between the 25 and 29th. I had sexual intercourse on the 26th my stomach has been nauseated and I'm always tired feeling kind of blah. If I did conceive and become pregnant when can I be able to get a positive pregnancy test. And my cycle is usually 28 days