You normally need to look at your book as a whole that is made of an intergration of text and images. Pages are most often done in two page layouts or spreads with double side printing you can easily fit 4 pages onto one sheet of heavy weight paper and have a 5 1/2" x 8 1/2 " book.
This is a book I am currently working on and have all the basic elements complete and may just fix mistakes in the copy and swap an illustration here and there.
This is what a soft cover will look like.