Toots, this is what I understand from reading Toni Weschler's book. Girls that are more learned amongst us, please do correct me if I am wrong as I am a newbie...
The time between ovulation and AF is generally consistent every month. I think this is called the lutenising phase or something like that. Its normally between 12 & 16 days I think (though it is different for everyone & can be less, which can apparently cause problems if its less than 10 day).
Its the actual ovulation point that changes, which can be moved around by any number of factors from health to other upsets or jsut your natural body. This is what impacts the overall length of cycle.
I have no idea how coming off the pill impacts all this as I was on a coil. That is, the pill isnt really you're natural period, so I am not even sure if you can use this as an indication of time between ov & af.
In short, I don't have an answer. Perhaps someone who's come off the pill can give some advice on this.