not everyone get's a true +ve opk (as dark or darker than control). I never did. I'd get one ALMOST as dark, but def lighter than control and then it's fade back to nothing again. I'd take the darkest OPK as +ve (so day 18) and say u O'd 1-2 days after (which is when they say O happens after +ve OPK) and then recommend testing 14 days after that. If you BD as often as u say, u should have a BFP soon honey! Goodluck!