Hello and welcome to YT!!!
He may have stopped growing. Trixie stopped growing right at 6 months. Scampers will be 6 months old very soon and he has not grown since for several weeks now. Some will stop at a young age and others will continue to grow until they are a year or a little bit older. Every yorkie is different so you won't know until he is an adult or close to it. Until them you just have to learn the yorkie shuffle, most of us here have learned it, less worries about stepping on your little one. Good luck with your pup and post some pictures
so we can see him!!!