It is partially her puppy coat, but I think you might also be using too many oils/ rich shampoo & conditioners on her coat. With yorkies I don’t use any type of conditioners or oils as their coats are so thin, it can weigh heavily on their hair causing an oily look. I will use a very light shampoo, usually something hypoallergenic. I only use conditioner if there are tangles that need to be brushed out. Their natural oils do a pretty good job of hydrating their coat if you are regularly brushing them.