Jason,

Yes, you're probably worrying for nothing. So long as your chapters aren't being lengthened by anything being repeated, or cluttered with boringly unnecessary details, you'll be doing just fine.

It's my opinon that, it's your story so it's your opinion on where the breaks should go that count.

Having said that, if it's really bothing you, why not have one of the other authors here preview your additions? Perhaps someone who has already read the first chapters, of your story, might have a good feel for it's flow?

Alex.