Its hard to say, some pups start out big and dont grow to much more after the 6 months mark and some start out tiny and grow for up to a year later and then some just keep growing.
If you search past post about size you will see that its pretty much all over the place. No 2 yorkies are the same.
My little (big
) guy started out big, He was a full pound at a week old, at 10 weeks he was 2.5 pounds,and at his last vet visit he was 5 pounds. He is only 4 months old.
He came from 2 4.5 pound sized dogs. All the estimates that Ive done say he will probably be around 8 pounds as an adult but I think he will end up being bigger.
You can get some idea if you times there 12 week weight by 2 you will get an idea at what she may weigh but I guess thats not always accurate either.