Positive hpt, negative doctor urine test?!

Guys I’m so confused... I got my first positive hpt on Friday, every day they’ve gotten steadily darker and today (Tuesday) the test line was as dark as the control line. I went to the doc to confirm and they said their urine test was negative!! What’s going on?! It is early (4 weeks +1 day) and my urine was very diluted- early afternoon, had peed recently and drank a lot of water all day. They’re doing a blood test but the doctor basically decided I’m not pregnant and seemed annoyed I wasted her time. I feel like there’s no way I could have had a strong positive this morning and in the span of 10 hours had a mmc and hCG already plummeted..