I just can't see space for growth...

While I wait for my 2 published books to go digital (very exciting and technical - not me at all!), I am looking at an earlier work with the possibility of having that turned into an e-book too. Although it was written for a slightly younger age group than the others and therefore is shorter, I've got a niggling feeling that it needs expanding. I just can't see where I could sensibly add to the story. I guess I'll keep reading through and wait for inspiration to hit (early morning walks again!).