I am quite sure there are lots of 7 lbs Yorkies being bred, as most people breed for the wrong reasons anyway....
Like I said, there's more to breeding than just weight and actually being prepared for when the pups arrive. Do you know your girl's complete background and lineage? I think most responsible breeders make sure that the #1 thing about breeding a female is making sure there are NO genetic defects in their line - BEFORE any weight issues of a female or male are discussed!
Best Wishes
