OPK Help?

This is my opk chart for this cycle. I normally have a 28 or 29 day cycle. I know not everyone ovulates on CD14 like some people say, but it's CD18 already and I haven't had a positive yet. From CD12 - CD15 I had cramping and on CD15 had a high, soft cervix with EWCM. I am thinking that's when I ovulated but I'm not sure. It's the darkest line I got then they started getting lighter again. Also, I've heard from some ladies that use these cheapies that the line never gets fully positive for them so idk of maybe that's what's going on. Thanks, any advice is appreciated ☺