Lines not getting darker!

Rachel
Okay, so I'm suppose to be ovulating today so I took a test (been testing the last 3 days or so) but the lines on my opk aren't getting darker. Getting really frustrated....I dunno maybe I'm off by a few days? I'm on my second round of Clomid. First round worked very well. Ovulated around cd 10. Now I'm getting nothing. 😫