If you can see well enough, the pic in my avatar is Ben at 12 weeks. Here is the YTCA site that shows pics of Yorkies at all stages of development:
http://www.ytca.org/pictures.html
7 weeks would be pretty early to be letting the puppies go -- maybe he is older (did you get papers?), but maybe he is just a big boy. Either way, I would just love him and let him eat a little more to support his size.