Can beta blood tests be wrong?

Lindsey
So I went to the er November 2nd I have a uti and vaginal bacterial infection I requested a blood preg test because my AF didn't show (Nov 2) and the test came back with a level of 1 so it was negative. But today I still haven't gotten AF so I took 3 pregnancy test red dye and all came up faintly pos? I'm confused any advice is welcome. Thank you