HHmmmmm.... maybe reduce the weight of that huuuuuge name that teeny weeny little scrap of Yorkieness has to carry around, LOL. Seriously though, he looks very healthy in his pic (and totally adorable.) When you feel his chest, can you feel his ribs? He may not be too skinny, but just adequately covered for his diminuitive size. If you are worried about a lack of weight gain, there are some great recipes posted as a sticky right here:
http://www.yorkietalk.com/forums/showthread.php?t=75933
Please keep posting pics and updates, I just love looking at your tiny little boy with the gianormous name.... he is just one little sweetheart!