Another question about coming off the pill...

I am in my 3rd cycle after coming off the BCP and have only started charting this cycle - mainly because I suspect I didn't O last cycle.

I have had temps all over the place, no noticible EWCM, and all OPK's have been negative. Its not looking great, so I am wondering if anyone else had horrid looking charts after the pill for a while.

Doctors all seem to say it will take 6-24 months (!!) to conceive after the BCP, but does anyone know exactly WHY? Is it because we stop ovulating, or is it just a hormonal build-up that can prevent conception?

So confuzzled! And DH says not to worry because I have only recently come off the pill - but I didn't think that should mean I don't ovulate at all...
I plan to go to my GP and get a reference for a fertility specialist if this keeps up, but I know if I went now I would probably just be advised to give it more time. So any imput from those who charted after the BCP (or who know whether I should be concerned about my lack of O symptoms after the BCP) would be highly appreciated!!