Hi Dragonfly,
It is possible to ovulate and not detect ewcm also! Just to confuse things. Since having babies I do not notic ewcm. I don't get a positive opk but I do get pregnant!
The opk thing is a bit of a mystery I think. Do you notice your second line getting darker? My advice is to test twice a day. 2pm and 8pm I noticed when I did this I got a dark line at 2pm (not positive but not feint) and at 8pm it was feint again. I bd that night and the next and viola!
The only opk that I got a darkish result with - 2 shades lighter than positive was lullaby.
Good luck Dragonfly
love and blessings,
Deb