I definitely need to get that book as I tend to get what I would say is multiple kinds of CM at a time. Last night for instance I had what looked like watery, getting to be EWCM, but part of it was also like sticky CM. How is that even possible?! None of it was semen as we haven't BD'ed in a few days,

, so I'm totally confused as well.
I can't help you with the OPK's as I haven't used them yet, but you know someone will be along soon to help you out!