Christmas has gone, but not Labman the grinch. Evaluate her using the method illustrated in this link,
http://www.puppychow.com/products/po...condition.aspx My guess she is too fat and will eat the rich stuff you are giving her, but not the chow she needs for a complete and balanced diet. Unless the vet is concerned with her weight, listen to the grinch.
Put down the dish with what the dog should eat, and give it 15 minutes to eat. Then take it up. Do not give it anything to eat until its next scheduled meal. In a few days, it should be eating what it needs. Continue to check its ribs and adjust the food as needed. This is not easy. I had a Shepherd go 3 days on a few nibbles. I was a wreck, but she was fine. It is almost unknown for a healthy dog not to eat what it needs. Unfortunately, in too many cases, it is less than the package says, and less than the owner thinks the dog should have. Many dogs are quite good at holding out for tastier chow. Like kids, sometimes it calls for tough love.
You might also consider adding another dog. You should have no problem finding a male past the puppy stage needing a home. That is what she should most likely accept.