If you notice two empty, white pages at the end of your Travel Book preview, here's what's happening: one of these pages, the left page, actually has space for a photo or a photo collage, and the other page, on the right, is a blank paper sheet that's always included at the end of every printed Travel Book. The left page can still be used as a photo page, but this is not visible in the Travel Book Editor. 

How to fix it

If you'd like to add one more photo page on the left page, you can open the editor and add a page at the end of the last step using the + button. You'll see that your total page count stays the same, because this simply makes the back of that last page available for your photo(s).