Help I don't know what to do

So my avarge cycle is between 24 and 28 days glow says that I'm 3 days late for af and but the other one says I'm sopose to start tomorrow now I have not been having any of my normal monthly feelings I have in fact felt sick every time I eat or drink abd have lower back pain and also mild tummy cramps usually I get like really bad leg cramps a week before but it's never been like this.. I took a test Tuesday night and it was a bfn so I'm just wondering what everyone else thinks should.i wait and see or I'd glow right that I'm late and should test again today.... I'm just so confused and I want this so bad. I have also never been more then one day late and glow has always been right on time with one day give or take so that's why I'm asking.. thanks