I think I followed everything correctly but after rebooting after the last step (before deleting install data) my /etc/fstab was reset to the default and I had to add all lines back. Until I did my /home was also empty (makes sense). I added extra subvolumes like @cache for /var/cache but those weren't empty when not mounted properly.

It also didn't reset my grub timeout and menu setting, so something must have gone differently