Hi! Congrats on your little girl
I don't have much advice on her coat as my girl never matted (I count my blessings on that one) My shih tzu has a coat that mats terribly and I've taken to keeping it short - seems like that is the type of coat a cotton coated yorkie has. But your girl is only 14 weeks old, so maybe her coat will change.
As far as her weight/size goes, at 14 weeks if she's already 5 lbs she'll probably be close to 10 lbs as an adult. A 10 lb dog is still very small, though. And you'll have more yorkie to love
