As you might already know Yorkie as most of the smaller dog breed are a little difficult to train. I have a Beagle/Pekingese he is one year old he is GREAT with potty training but took a while for him to understand that he should only potty outside. Now i have a 4 month old Yorkie. She knows when we take her outside that she needs to go potty and she does it. I started her with crate training her so she didn't go in her crate she passed that with flying colors, we got her when she was 12 weeks and i can say she honestly has not gone in her crate. Potty though she still has accidents MINOR ones in the house.

Good luck with your little Love bug.