We got our Lexi the smallest size. It seems to fit her fine and if she tops off at 10 lbs it would be ok. But I do wish I would have got the little larger one.
Some of the wire mesh crates (which we got and I like very much) have a divider walls, so when they are really little you can put the wall in to keep the space smaller while they are being potty trained! Just ask at the pet shop and remember most stores will not let you return it so be sure you will be happy with it. And good luck with you new puppy!
