This is taken from the Yorkshire Terrier Club of America's Code of Ethics:
A member’s advertising shall not use terms as “teacup”, “tiny specialists”, doll faced, or similar terminology. http://www.ytca.org/frame_index2.html
To give you an idea how big she'll be, double her weight at 13 weeks.
Unfortunately, it seems like your breeder wasn't too ethical, but there really isn't anything you can do about it now. No one can predict adult size and as far as "champion lines" go, a prospective buyer should always ask to see the parent's pedigrees.