Apple photos stores the album information in the photos library whether you have iCloud Photos enabled or not. It also stores all photos by default in the same library so unless you added photos stored outside the library and referenced them, everything will be on one backup normally.
- Make a final Mac or photos only backup now and try to avoid taking new photos you can’t afford to lose. I recommend downloading all originals on one Mac to ensure you always back up the full versions of all iCloud photos.
- Inventory your previous backups to determine the last time before the change which you will attempt a restore.
- Restore from your backup.
- If the albums look good, check if you lost any photos (using your inventory results from step 2) depending how many photos are missing, you might need to restore from #1 and export them to a folder outside the library and then repeat #3 and #4. Import the missing photos after the restore and check are complete.
- Make a current backup that has all photos and all albums.
If you find you don’t have a suitable backup on #2 at least you’ve started now with one current imperfect backup and can then start making albums from memory that you determine you need and be ready with local backups should you need that again.
Even if you use iCloud Photos, it’s important that you always back up your library locally using one of the following methods: Time Machine or manual.