I think your female may be a cherryhead. If you post a pic of her plastron it would help. If she is eating and moving around like the other one I wouldn't worry. Do you soak the torts?

Your vet does not seem to know what he is talking about. I may be wrong, but it is my understanding that torts continue growing throughout their life and just slow down as they get older. I am interested in how the vet knew how old your torts are. They both look fairly young to me.