Very clear BFP on FRER and Dr is saying their test is negative???

Yesterday morning I got a light, but visable positive on a First Response. My OB wanted me to go to the lab to confirm with another urine test around 3pm...they wouldnt give me the results there. When i got home from work around 530ish I took another FRER and the line was much, much darker. My OB just called and said my test came back negative. What is going on? I'm so upset. I've already had 2 miscarriages (last one was 9/1/16) and one chemical. How could their test be negative when my home test is clearly positive??!???