I'm not going to be mean - or say anything offensive to you - but I will say (as nicely as possible) that to me, it just sounds like you haven't done a whole lot of research on this breed

Which is OK - because ALOT of people make that mistake in the beginning and SO DID I. I think ALOT of us here did.
Now as for you saying that you want to find a "good one" - I personally don't think you necessarily mean that the one you have now ISN'T good - perhaps you just meant that you want to find a "good"
"teacup" (
MEANING - the size you want, the cute factor, etc.) so I won't jump to any conclusions (bare with me here YT members, I am TRYING TO BE NICE lol). I'm sure you love the baby you have now - I guess you are just looking for something smaller, which is totally FINE. There is NOTHING wrong with that. I have a bigger dog and although I love her very much, I was ALSO looking for something smaller - which is why I became interested in the Yorkie breed. But anyway -
Just be sure that you do your research on this breed. No, there are no such thing as teacups, and YES...breeders WILL sometimes try and tell you that YES, you are in fact buying a "teacup" when in all actuality it is just a sales pitch used to make people THINK that they are buying a "special, tiny" dog. And just so you know - NO (and I do mean NO) breeder can GUARANTEE how much a pup is going to weigh when he/she is full grown. They can only give you their BEST GUESS. Now, alot of times you (or the breeder rather) are able to tell whether a pup is going to be on the larger or smaller side when it reaches adulthood, but the exact WEIGHT is NEVER a guarantee.
There are growth chart
estimates online - just do a search

My best advice to you is to do AS MUCH research on this breed as possible before you go out and buy other Yorkie

AND - your at the best place to start your research
Good luck in finding your new baby