Dixie is three and I've had her since December and she still won't let me know that she has to go out. I let her out about every two or three hours and I have recently purchased a doggy diaper for her to see if that will help keep her from going in the house. I am hoping she won't want to potty in her diaper and will start telling me when she has to go. I have been using potty pads also and she's been good about going on them when I have to be gone for more than a few hours. She stays in her playpen when I am not able to supervise her. Hang in there, just look on the bright side, yorkies make small messes. You could be in my shoes housebreaking two Bernese Mountain Dog puppies and a yorkie!
My Berners pee lakes and poop mountains and it takes a half a roll of paper towels to clean it up, but they are catching on quickly.