Help! Question

So I just came back from the doctors for a regular check up and they did a urine test. I’m only 8DPO. They told me it was negative which I kind of expected as I think it’s too early and it wasn’t with fmu. They wanted me to do an X-ray (long story) so I tell him that I have been ttc and that I know I’m only 8DPO because I track my ovulation so is there any way I could still be pregnant as I don’t want to harm the fetus. He tells me there’s a very very very small chance as if I was this would be around the time when I should be testing positive, so the chances are very low. Why can’t I believe that? I mean my period is still not here. And I’m only 8DPO! Idk what do you guys think? Do I still have a chance? Or the test they do at the doctors are 100% accurate as that is what this doctor sounded like.