So I bought a huge box of tests from Amazon. About a week after my period I decided to try a test to get the hang of it. I had a faint line which was really strange because glow didn't predict my ovulation for another week. I took another test the next day and it was very dark. Definitely positive! So I'm thinking maybe this has been the problem! Maybe glow was wrong. Hubby and I get down to business every other day legs in the air etc.. Took another test a couple of days later and line was very faint. So I was fairly confident that I hit my window.