Chapter Breaks are Wrong

I've created an ePub book using Sigil and am trying to get the book formatted properly for iBooks. The TOC is fine, each "Chapter" is in a separate file - which is where I want all page breaks to be, and all is well except one thing. The "# pages left in Chapter" at the bottom of the page in iBooks is picking up ALL my headers (even subheaders within Chapters) as new "Chapters" and, therefore, miscouning how many pages are left "in this Chapter".

What is iBooks looking for as far as what consistutes a "Chapter" - ? Is it going by the navpoints? I wanted all the subheaders in my TOC - but NOT for each to be counted as a whole "Chapter" by iBooks - what do I need to do to get this to work properly?!

Thanks so much for any help...

- Jacki