Sashba I am another OPK misfit. I never ever got a positive OPK. I could get a second line no problems but never got a true positive. I used two to three a day from the day after AF finished until I got AF next. Even the cycle I fell pg I still didn't not get a positive OPK. So don't worry if you don't get a true positive cause you can still be ovulating just fine.
Good Luck.