You’ll need to paste the contents of your yml file. My guess is that when you made your custom yml file you didn’t create a persistent share for your database.
I guess you don’t have backups it if you did, they too existed only inside the container.
You can look in the samples directory for how those should be set up. If your other one is done the same way, you’ll need to go into the container, stop postgres, and copy the files out of the container, or configure S3 backups and make a backup.