First I want to say to the original poster, hang in there it does get easier as they transition out of the puppy stage. We would never expect an infant or newborn to be pottty trained so why do you expect the poor pups to be? Consistency is the key with potty training so be prepared to have no life until they are fully trained because that is the kind of dedication it takes.
For those breeders that said they would never sell to someone who works

Ummmm I know I'm not made of money, but I make the best yorkie mom. These little babies cost a lot to care for and expect to be spoiled and that requires money. I'm a unmarried young woman who loves her yorkie to death and probably has one of the most best behaved and best trained yorkies. I work a full 8 hour shift after which I come home and am her slave

Just because we have to work doesn't mean we're not fit to be good homes for yorkies. Trust me, if I could I would stay home and work from home or not work at all. But I don't have that luxury. No offense but I hope other breeders don't have your mentality because some yorkies might be missing out on perfect forever homes because the person has a job

This wasn't directed at anyone in particular. I just saw it posted a few times and it struck a nerve.
On a side note, Coco is by herself from 8am-430 pm, and she has been in that schedule since the first day I brought her home. Haven't had any training or behavioral issues and she really hasn't been sick. I don't trust people going into my home without me there so I will never hire a walker and I don't trust workers at a daycare to care for her like I do. So she is perfectly content sleeping at home. She has run of the dinning room, livingroom and kitchen. I don't think she minds getting some quiet time.