Did you ever get any help with this?
I'm having the same issue.
I've uploaded my book, am only having some trouble with page breaks and it says right there, pagebreaks may look differently on Nook, download Nook for PC to preview.
I downloaded Nook previewer, but my file still won't open on there, so I still have no way of knowing how it will *actually* look.
I see people recommending Calibre, which does not work for me - it shows my indents differently than Nook picks them up, so I can't use that for comparison.