My dog was a little over a year when he came home with me. He's not a yorkie ..he's a small poodle. However, it was the same exact thing you are describing. I bought many different types of toys, and with the squeaker toys...it would get his attention when I squeaked it, but he wouldn't touch them. I too was worried that he might never play, because with mine, it was very clear that he didn't even know what toys were.
He wouldn't even touch any type of kong filled with every treat I could think of..nothing. I was doing clicker training with him because my dog had clearly missed very critical socialization of anything and everything possible. I also began using it with his toys ...just to teach him it was a good positive thing to go up and touch his toys. But other than walking up and touching them...still nothing. I continued to try to initiate play with his toys and I put some in his bed and house. He never responded other than touching them with his nose occasionally. Then one night I'm cooking dinner and I hear this squeaking start, and once he started ...it was like he couldn't stop! It was if he had finally realized all of the fun he had been missing all of this time. Now there isn't a day that he doesn't squeak one his toys.
So, maybe it could be that it might take him a little while to fully settle in. Either way, I know he is going to bring you so much joy!!