My due date is may 10th 2015, doctor says i concieved august 3rd, i thought first 2 weeks your not considered pregnant yet? when did conception occur?

August 12-16: If your due date is May 10, you most likely conceived between August 12 and August 16. Conception at this time could have been from intercourse 4-5 days earlier. August 3 is probably the first day of your last menstrual period, not the date of conception. Pregnancy is dated from the LMP, not the date of conception. By this convention, you are considered 2 weeks pregnant at conception!