Personally, I tend not to worry about chapters until I'm done writing the first draft-there's plenty of time to slice it up once you've got the story down (you can always add stuff or take away stuff at that point and you'll see where the breaks should come more easily). If you want to write in chapters to get the pacing right though, just be open minded. If you've decided that the chapter will end at a specific point and it winds up being too short, then think about another place to end it further on. Basically, don't worry too much about length in the early stages, you can always shift your chapter breaks around, add and remove stuff once you know the over all shape of the story.
(Of course, someone else might have a completely different view to me-I tend to write stories from start to finish and then puzzle out how to make them into something neat)
Also, just a quick, general reminder that anything you submit to us for points has to have been written in May.
"Does the Walker choose the path or the path the walker?" -Garth Nix
"Without reading, we are all without light in the dark, without fire in the cold."-Tamora Pierce
(Av/sig by Amy!)