Glow says I'm ovulating but tests are negative!!

Hello everyone,  me and my fiancé have been ttc for 5 months. This is my first month using opks and I'm starting to feel a little concerned. In the past I've tracked ovulation by my CM and glow is usually spot on with the date I have EWCM which would indicate ovulation. As we aren't having any luck I thought I'd try ovulation tests. I've been testing for the past week and there is nothing. Perhaps the slightest wiff of a line but it's barely visible to the eye! Today I am supposed to be at peak fertility/ovulating and I took a test and there's nothing. I should've had a postitive yesterday if I am ovulating today, right? But there is nothing and I'm now becoming increasingly concerned that I'm not actually ovulating at all? Has anyone experienced anything similar? Or perhaps had negative opks and then gone on to be pregnant? I'm not sure whether the tests are dodgy or if there's something wrong with me!