How common are false positives with blue dye tests?

Long story short. Thought i got my period. Been bleeding off and on for 9 days. Had pregnancy symptoms in the beginning for two days that dissapeared once I started bleeding. Passed white tissue And have been cramping. 
I bought a blue dye just to see if i was pregnant and was maving a msicarriage or if it was just a weird period. Two test had very faint lines, i had to tweak the pics just to see the line. I asked my fiance to go buy me a pink due test but the dummy came home with blue because "the box was pink" 🙄. One test had nothing where the other test i took with my morning pee had a bfp.  So im just confused. Im calling my ob this morning but what are the chances theyre false positives?