You know, I'm confused too!
I'm O day was supposed to be CD14 but i had EWCM today so that means I O.ed CD12. The OPK yesterday, Lullaby Conceptions showed me a faint line, but another brand Discover was -ve. This morning Maybe Baby gave me ferns. I will test w Lullaby again at 2pm. They are supposed to be a lot more sensitive and pick up O better than the other brands.

Having said all that, my best bet is to listen to your body then all the tests. The tests help to predict but monitoring your mucus is the best way to go, I think.

Last cycle I was dependign on Maybe Baby and got very frustrated cos it didnt show me Oing. I should have paid better attention to my body. So I dont know if I O-ed at all last mth. Since then Ive started using OPKs just to make sure.

Maybe your cycle is different this month? Did you try the OPKs yesterday? You are right, they say that you O 14 days before the first day of ur next cycle but this looks early than normal as your cycle as 30 days.

I'm not sure what is the best. Maybe start a record of your CM and test today w the OPK?
It takes a few cycles to understand how it changes. Maybe try OPKs until your actual expected day of O, CD15 and see if you O then. Could it be you O earlier in the cycle and have 22 days of none fertile? Or maybe it's just this mth? The O day isnt always fixed, I read that for some women it can shift within 2 days and others more.....

Sorry, I hope I didnt confuse you, I'm learning myself so I've also been asking myself these questions.

Can someone else help?