Are you pad training or outdoor training?
ZoE was fully trained & had the run of the house at about 16 weeks old. She's now 9 months old. We've had no accidents in between those times at home or when visiting friends/family. She knows to go on her pads no matter where they are. I've always pad trained my yorkies and found it very easy to do, but it requires putting your life on hold for a few weeks and doing nothing else.
I've never outdoor trained a yorkie, so can't speak to that. Infact....I'm not sure ZoE even knows its ok to go outside
. Even when we are at an outdoor event/festival, I have to put her pads down to get her to go...lol