My boy is pushing 6 years old and I am starting to think of a second Yorkie. He is larger, pushing 11-12 lbs, not fat, just "big boned"

. We have friends with more typical Yorkies 4-6 lbs and they are just too darned small for our druthers. We have becomed accustomed to Yorkies of Substance

.
Are there any breeders who "specialize" in larger than standard sizes?
Also wondering if adding a second Yorkie at this stage should be another boy or maybe a girl?
thanks,
Samc