Could the hospitals pregnancy test be wrong?

I went to the ER for kidney issues, I told them there was a possibility I was pregnant because 2  weeks before I was TTC, the urine test they did said negative but I think it was too early to tell. I feel like they should have done a blood test , I am almost a week late on my period but don't want the heartache of seeing another negative test. :/  I also have sore breasts. Am I crazy for thinking there's a chance I am pregnant ?