Kindles do not use page numbers only locations which are more accurate than page numbers. Page numbers will change depending on the size font used but locations will remain the same.
For some folks locations are annoying but that's the way it is.
The best way to try to find where you left off in your book is to use the search function. If you can remember a phrase or something unique on the last page (or near the last page), use that as your search term and the Kindle will find it for you.