How do I view ALL my photos in Google Photos on mac?

Question

On my iPhone I can see all my photos in Google photos app, however when I open google photos in webpage on my mac only a random selection are there. I have installed backup and sync.

Big picture is that I would like to wean off iCloud photos to save on storage space, but don't want to do that until I'm sure Google photos is working properly, and it doesn't seem to be yet.