Hard Drive Full, can't figure out why
Assuming your directory is correct, you have the following folders to move off the drive or to thin out:


558 GB photos library
67 GB Windows 7 disk image and files


If you have a good backup, you should be able to simply copy those to an external drive, train them and see that all the space you expect is freed.

The virtual windows files runs great on an external - and thinning it might be tough. 

Photos is a little easier to rebuild and clean up - you might need a tool like Power Photos if you don't like merging libraries or have a good strategy to move some files to a secondary library or would be willing to move the primary photos to iCloud and let photos only store thumbnails / free up or "optimize" space on your Mac.

I wouldn't do cloud first unless you are sure you archive the originals or can walk away from photos if iCloud crashes or corrupts things, though.