My yorkie girl is 15 weeks old now, and she is -almost- fully potty trained. You know what helped me a lot? The Japanese. Yeah, that sounds really funny if you think about it but they have this whole effective method of indoor training dogs ( even big ones like labs ) because most people in Japan don't have homes with a garden/yard. They use a different style of crate training than we do in the west, and let me tell you its effective. What you do, is get a square pen, or a xlarge crate and put your yorkies bed on one end, and a pee pad tray on the other end. You keep this in the same spot as they are adults and they learn this is where they potty. Here is some video links to show you what I mean, also DONT CARRY the dog to the potty area, play with them and lead them to the potty area, if you constantly pick them up and plop them down they will learn that unless you're there to always pick them up and stick them on the spot when you arent there to do that they pee anywhere because they havent learned the footsteps to their potty place. Plus they are enclosed so cant go pee anywhere else. As they get more familiar with their comfort zone and pee area they can be let out by the little door and roam around the room and they will keep going back into the pen on their potty spot. Eventually the bed comes out, so they have house freedom but the tray always stays. Very simple and effective! Much nicer than keeping them crated all day. You don't have to be able to understand what they are saying, just watch the two videos and what they do as an example!
The first video is for training to go in the confine area to the designated spot. Second video is for outside of the enclosed area and leading them to the pad.