The reason the insurance company has not processed the referral was because it was never submitted. The person who assured me she had turned in the referral thought I was asking about something else.
She is now on the phone to the insurance company and will call me back. Update: She just called--and contrary to what I was told last week, the person she spoke to, named Eloise, said that no referral or authorization is necessary!
Doh! All this concern for nothing! Goes to show you that all will be well, all will be well, and all manner of things will be well.