Hi BJ, welcome to yorkie talk.
It is a very exciting time when our babies are pregnant, but yes it can also be very scary; especially with one as small as zsa zsa. But it has been done before and is possible for her to have a trouble free whelp. A very helpful key is to LEARN AS MUCH AS YOU CAN BEFOREHAND, HAVE YOUR VET OR AN E-VET CLINIC AVAILABLE SHOULD YOU NEED THEM, and BE PREPARED. If she tied with the male at the end of November, then she is probably due around the end of January so you have at least a month to read as much as you can. Many of us here on YT will gladly help anyway we can and you can also find information to read on past threads (do a search on pregnancy, whelping) and I also highly reccomend going to this website
Canine Reproduction Video and Book on Breeding and Whelping dogs by Debbie Jensen for dog breeders and Whelping Supplies needed to deliver puppies. . It has information on just about anything you will need to know from the heat cycle to the weaning of the pups. Go there, read it, re-read it, print things out, and re-read it some more. It was very, very helpful for me.
Good luck to you and zsa zsa. Please keep us posted on her pregnancy & whelping. We're here for ya!