I stuggled with the same thing, I was worried whether or not my chapters were too short and or too long. So with Twilight heart I decided to write them as if they were a TV series. I also wrote them in a book and made a limit of 5 or 6 pages for each, you colluded try that too if you like. If not have a look at published works to find the style you'd like to take. Hope that helps