They count from your last known period so at conception by their way of calculation you are already two weeks pregnant. I hope this helps.
Hello,
Pregnancy occurs only during the time of ovulation. Ovulation is the release of a single, mature egg from a follicle that developed in the ovary. It usually occurs regularly, around day 14 of a 28-day menstrual cycle. If your last periods was on 9th June then ovulation would have occurred on 28th or 29th June when you had intercourse.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
They go by your last menstural period as they really can't predict exactly when you ovulated with ease as there is no set, "Oh, every girl ovulates on day x of their cycle." That's how.