Wow that's a lot. But that's a good thing, all the custom stories out right now seem really short. (I haven't actually played too many, but from reviews they seem short) Mine is currently about 6 maps but there is still a lot of room to expand the story.
The problem with so many maps is that in order to be any good they have to be well thought out and detailed, so it takes a long time!
Anyway, if you have a basic idea for one of the maps you need done, I could work on one in my spare time for you. Just out of curiosity, what is your story about?