Your screenshots are showing an iPhoto Library. But where is your Photos Library?
You Pictures folder is much smaller than your original iPhoto Library.
Tony is right, that you should save your old iPhoto Library on an external volume, until you are sure, that your Photos Library is now holding all photos and videos and they are all working properly and not in an older legacy format, that Photos cannot process.
As you are using "optimise Mac Storage" in the Photos > Preferences > iCloud, a Time Machine backup will not suffice to make regular backups of your photos and videos. Time Machine can backup your Photos Library, but the Photos Library will be incomplete; you will only backup the databases, but not all originals photos, because many of them will have been replaced by smaller optimised versions for browsing. You can save the original image files by exporting the originals to an external volume, whenever you import new photos.
Because it is so difficult to backup the photos, if "optimise Storage" is enabled, I do not use it. I am using iCloud Photos only for syncing my devices, but not to save storage on the devices. That is making it easier to keep my documents and data properly backed up.