Slightly confused..

Friday a.m I woke up and decided to take a test (16 dpo) and got a vvvvvf positive. 1st pic. So I got all excited and decided to take 2 today Saturday a.m, one of them being digital (17 dpo) and they were both negative. 2nd and 3rd pic. Maybe my levels just haven't risen enough to darken the line? Or maybe I just had a false positive? I'm supposed to start Monday. 
All advice would be appreciated.😓