doxxielover, you're my hero!
Apparently, the game makes automatic backups (I guess each time the second to last save data), so I could just copy the content of the backup file to the new file, and there it was!
This saved my day, thank you very much
btw, Pam, you were right, the problem was the original household, I guess it's because there's just one bed for two sims? I don't know, but I bought a new bed and the problem was gone. Thanks for the suggestion!