The main limitation of the wizard isn't how many spells he can learn but how many he can prepare at any given time which is your level plus intelligence modifier...so at level 12 you will have 12+5 so 17 most likely unless we can find something that allows us to break the 20 intelligence cap which might bring it to 18 or 19.
Well, my post was about how many spells a wizard can learn, not how many they can prepare.
