What a pretty li'l thing.
I'd grow it out.

I think all Yorkies are beautiful but there's something about the medium to long hair that just makes me go aaaaaaaahhhhhhwwwww.
We have a neighbor down the street who gets her Yorkie shaved everywhere except the tail, legs and face..that's really pretty, too.
I say, if she's eager to be groomed, try everything until you find something that you like on her, and that she is comfortable with.