She’s reacting that way because the pulling on her hair - the longer hair needing upkeep - the detangling of it, HURTS her. Yorkies have very fine hair and pulling it out, HURTS, no different than a human. That’s your dog trying to tell you she’s in pain and you’re not getting the message. Unless you’re showing her, and now with her having been inadvertently “trained” to hate grooming/getting brushed, (which could have been soothing), why not keep her in a puppy cut to ease her stress and unhappiness? You’d have a happier dog and a happier relationship with her.