It is hard to tell from these pics alone, but I don't see anything that screams mixed dog. Depending on how you groom the hair on the ears, yorkies can look just like that. True they are a little on the large side, but there are many yorkies with large ears. I would believe the registration and breeder since there is nothing that really stands out as another breed. If there was papillion in there, I would suspect white would show on the coat. Maybe not, but I sure would not think it merely because of the ears. They look as much like yorkie ears as papillion. My mom has 3 papillion and they are a lot different too, like yorkies. Everyone can see different things in a dog. When I see the pointy nosed dogs I see fox. I am sure they are not being bred with fox but that is the image in my mind. Specific traits mean different things to different people. Big ears may remind some of a papillion (especially when the hair fringes like yours), but others think chi as in this thread. Still others may see a different breed. But I see yorkie -- not a show quality yorkie -- but
a yorkie to love forever! One that obviously is bringing you years of joy already and will for a long time to come.
The reason I encourage only breeding TO the AKC standard is to try to minimize questions like these. When breeders are not careful to select only those dogs who epitomize the breed standard for their dams & sires, they wind up with too many puppies that are far enough off standard to cause the owners to ask questions like these as they mature. Even selecting the best breed representatives, there are going to be some that are off-standard. But when you start with a breeding pair that do not meet standards, then the chances of getting pups that mature into the dog most think of as a Yorkshire Terrier get slim to none.
Very selective breeding is the answer to preserve our breed! If today's breeders are more responsible in selecting which ones they will breed and go ahead and spay/neuter the others -- our children, grandchildren and beyond will get to enjoy the beautiful Yorkies that yesterday's breeders devoted their lives to refining!