I'm sorry but I have to say, a Yorkie's size and weight DOES NOT matter, unless of course you plan on showing her as the AKC standard is 4-7 lbs. If you aren't planning to show her, then I honestly don't think you should worry about what her weight is. I am not trying to be rude here AT ALL....but I have to say, there are far too many people out there that worry about their Yorkies weight and size. It is just something that really gets under my skin. My Yorkie's are by no means big, my "biggest"
is 4 lbs and I do have a very tiny girl, but I can tell you that they could BOTH blow up to 20 lbs and I would care either way as long as they were healthy.
I don't think there is anything wrong with liking the small ones, but honestly - I know some people and their dogs weight is ALL they think and talk about, and I'm sorry - but it's VERY annoying.
Again, not being rude to you what so ever, just trying to give my opinion on this issue as it is one that truly does get under my skin. I truly do hope that you will love your baby no matter WHAT she weighs, or how big she gets. After all, it is not something that either you, or HER can control.
Oh and P.S. - just for the record, a 5 lb Yorkie is by NO MEANS "big".