Normal OPK? Did i just not ovulate? I'm confused

Every month I go from absolute negatives to absolute positives. But for some reason this morning I had a test that was almost positive so I thought for sure it would be an absolute positive when I got off of work today. I got off work and my test was lighter than this morning. Then i tested again a few minutes ago and it was even lighter than when I got off work. So did I just not ovulate this month? Or did i maybe ovulate early this month? Glow also predicted that I was supposed to ovulate today and so far it's been pretty accurate on its predictions. Any advice? Does this just happen sometimes? Thank you❤❤