Lucy still has her puppy coat. It's starting to grow out (Her black is changing to blue down the back.) I've had some difficulty with matting on her legs.
I was told (here
) that the adult coat is different from the puppy coat. Maybe you just have to wait it out. Also, you may have an outlier from your breeder's line. Even if most of the yorkies are silky textured, your puppy may be the one that's not. It's a wait an see.
Good luck.
Tracey