Good news
Maybe just keep him in a sweater or shirt for extra warmth. Did you actually see the 12 lb. mom and the 2 lb. dad???? That's a little curious. Did she breed the male and femal on purpose?? It's hard to even imagine that being possible
You are supposed to double the 12 week weight to get a rough estimate of adult weight. I'm guessing he'll be in the five lbs range which is a great size!! My Bailey is five lbs.
Hope you stick around and hang out! I've learned a ton on here too
It's more fun to post when they aren't sick and you aren't worried!!! Never a dull moment with one of these little munchkins