Are you just using opks? Or are you temping etc? I gave up with all that stuff, I was getting too stressed, so now I just have sex every couple of days for the middle 2 weeks of my cycle. It's not working yet, but I'm not stressed!
You might have missed ovulation if you had a dark one which hasn't been positive, or maybe ovulating later this cycle? Fingers crossed it suprises you tomorrow and you get a nice dark positive ov test.
Big hugs, ttc is horrid at times! The entire group I was part of before is now over on the pregnancy boards, just me left ttc!