Hey guys, (i meant to put is my yorkie pure breed, ignore my typos

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i have a 4 year old Yorkshire terrier named Coco. i never really doubted his breed considering i got him from a breeder a few years back. The day i got him, he was 6 months old; the breeder showed me his parents which both appeared to be both yorkies. She claimed Cocos mother was a show dog and has "champion blood", yet i got coco for a pretty cheap price. ($600) she gave me a booklet of all his vaccinations, but told me she would "mail" his AKC papers to my house. I never did receive anything from her, i gave her a call after many years, (i know stupid of me) to see if i can get a copy of his AKC papers. She told me she sent them and if i never received them, then its not her problem anymore.
Many people question Cocos breed, and think he is a mutt. Many people tell me that yorkies are supposed to be 5-6 pounds, silky long hair, tan- to black coat. 7-8 inches tall from the shoulder. however, coco is a whopping 10 pounds, (i dont over feed him) he has silky head, but a wooly coat on the rest of his body..
what do you guys think? could he be full breed? or a mutt?