Confused

Thursday night I got a clear negative on a blue dye test. Friday morning I got a faint positive (after being up all night due to working night shift). So I drank my soda and went to bed. I went to bed around 8 AM. Got up at 4 PM. Took another test, and it was negative. So I’m confused now. Was the othwr one a false positive? Or was my urine too diluted when I woke up due to drinking so much before going to sleep? Or what? Any advice please??? As of today (8-11-18) I am 10 DPO. AF is due the 15th.