not that size matters....lol
. But when I spoke to my vet he said that they are pretty much done with their growing at nine months and that is also when he said that it was a good time to switch to adult dog food. That is also what the breeder said and also two of the yorkie breed books that I read. I guess you can't really tell because there are small dogs out there that their pup grows much bigger. Sometimes size from way back in the breeding line can pop back up again. The standard from what I know is between the 5-7 pound range. Lex is almost six months now and weighs about 5lbs. I am so curious to see how big he will get.
Hope it helps. By the way your pup is totally adorable.