Hmmm, my first furbaby was at her full height by 7 months. She continued to gain a few ounces. When I brought her home she wasn't quite 2 lbs. At 18 months she weighed almost 4 lbs. She never weighed more than 4lbs. I am thinking that maybe the bigger yorkies continue to grow up to a 1 yr-18mths. The smaller ones seem to reach there full growth, sooner. That is just my opinion....I hope this helps! Congrats on you new furbaby! No matter what their size, they are all adorable!!!!
