I agree with decaturbride (and actually got pregnant the same month I used the CBEFM I got from her!!). Keep going and don't give up. My cycles were way off. When I used the monitor, I went from low to "eggie" overnight so that might also happen to you.
I don't usually O until CD 18-21 so maybe you're having a late O. The cycle I got my bfp I never thought I would O and I finally did on CD22 so don't give up hope.
I ovulate really late as well (was around cycle day 19-20 before Jack was born)...and the month I got pregnant with Ethan was probably day 25 or later, I had actually given up on the OPK's and ovulated after I stopped testing!
I was also a really late ovulator and found the CBEFM to be so helpful. I was more depressed when I had no clue what my body was doing! Hang in there....it just takes some time sometimes.
Re: cbefm is depressing