My photo album is EMPTY

Check Photos>Preferences--the library name and location are at the top. Maybe the wrong library is being loaded.

Try closing Photos and then option-click on the Photos icon. This will show the libraries that Photos knows about. You may find your library there.

You can also search for libraries, since the extension is ".photoslibrary" by using the search field in Finder. See if your library accidentally found it's way into a different folder.