I, too have a Yorkie your size and your age.... We have the wee wee pad in our house and she had 2 accidents in her life.... Even when she is eating or playing, she will stop abruptly and go to her wee wee pad. She has been roaming around in the apartment for the past several weeks and often we wake up to her pooo on the wee wee pad. When she first succeeded, we gave her a treat ( they like honey comb ) and we prased her a lot. After associating praise and reward, it only took her that day to learn where to pee and poo...
Hope this helps.
