@astra_underscore do you have lvm volumes, or are these regular traditional partitions?
With LVM, you can do a very... time consuming partition-shift operation "left". But regular partition tables would need to be converted to LVM volumes first, or just manually cloned to the left, letting you delete the original partition afterwards.
Either way. Make some soup or something. This is gonna take all day or several days even. Aren't disks fun :3
Maybe shrink the partition to exclusively the utilized space and little more. Then it will be less expensive to clone it with special tools.
@astra_underscore yeah some mistakes are uh... very costly in terms of time. Having a spare disk would make it simpler, so you can just retry with a backup.