POSITIVE full ferning but negative OPK!!!??

Ok, so my cycle has been pretty out of whack! I was on the mini pill for about a year and just came off it. My last cycle was like 31 days (I am usually a 28 "cycler")... But this cycle I guess I will prob OV around  CD14-15.. 
Anyways, i have taken OPK's EVERY DAY 3 times a day sometimes, for 6 days in a row... Opk didn't even have a second faint line except for yesterday (CD14)  it was just visible. Also yesterday I had "FULL FERNING" though...?? Today is CD 15 and the day that fertility friend predicts I will ovulate. I have NOT been doing temps this month but probably will next month. 
I have conceived 2 children naturally and fine. I have one 5 year old and one 2.5 year old. Never MC'd before either. 
Now you know my history, my question to you is... Do you think I could have still O'd even with a neg opk?? 
Also, my CM hasn't been promising! Only yesterday was it slightly fertile looking ... In the morning it was watery and the evening it was sort of like EWCM.. But all the days leading up to yesterday, and now today, it's has been white and stringy. 
When are you suppose to fern?? Is it the day before ovulation like an opk? I'm having difficulty finding this info on the net. 
Any of you get a NEG OPK and POS ferning and end up pregnant!??