opk stopped working now on day 37?

Elizabeth • TTC baby # 1 with my wonderful man. :)
This month I started taking my opk's like normal but after a few days of negatives it stopped working. I can't remember if I had any ewcm or not bc I usually don't have very much. My periods go from 28 to 35 days or so they do vary. Now I'm on day 37 and don't know what's up? Glow shows it starting day 39 bc that was two weeks after I stopped taking my opks. Not sure if I should test or wait?