I don't have any insight on this either, but I could not help but notice how young Molly was when you got her. I keep seeing that over and over again on this website, and it is heartbreaking.
Here is what the book "Yorkies Head to Tail: the essential Care Guide" says:
". . .I recommend that a breeder keep a puppy until 16 weeks or more. When I hear of puppies being sent to a new home at 7 and 8 weeks, I am appalled. Most new owners are not knowledgeable enough to tke care of a puppy that young. A 7-week old Yorkie is just cutting its teeth, being weaned from its mother, having its first vaccinations, adjusting to new food and the world. To spring upon them a completely new environment and new people is too much, in my opinion. It can leave the dog bewildered and fearful, and you want a Yorkie that is confident and adapts well to new situations."
I would be suspect of any breeder who would let a puppy leave its Mama at 7 weeks, and I hope that you can all help spread the word that this is wrong. Yorkie puppies aren't like labrador retriever puppies.....