If you DTD the day before your last AF and that was it.. i would highly doubt you are. How long is your cycle? On a 28 day cycle, you dont normally ovulate until around day 12. Sperm can only live around 5 days max. So unless your cycle is super short i wouldnt think you are. Being stressed and worried about it can actually mentally delay AF. So i guess for piece of mind you can do a test.. then you will know either way.
Best of luck.