Sorry about your housebreaking problems.
I'm always surprised to hear that people are having very difficult times housetraining their yorkies, as I've always had an easy time of it - UNLEss the dog has been sterilized very young. I hope your female isn't one of those puppies sterilized while a baby - because in that case the prognosis for housetraining her will be bad.
I've trained 3 male infants and 2 females of this breed over the course of 25 years or so and never had problems - the latest being a 4-1/2 lb uncastrated male who was completely housetrained by 4 months and has never had an accident or marked in the house. (He's now 8-1/2 years and can easlily go 8 hours without a bathroom break although he ususally only has to wait about 6 hours.)
Unfortunately, the Yorkies I've rescued were a different story- some being very difficult to rehabilitate- people can manage to screw the whole process up royally - mostly by LAZINESS or CRUELTY.
I think you should forego the litter box. Use a small bathroom with a baby gate ( a different one that she can't escape from). If possible have someone you trust come to take her out after 3 or 4 hours. If she has to wait the entire time you're at work, you have to expect it to take a lot longer. Leave a small amount of paper in a corner. If she doesn't use it, she doesn't.! The idea isn't to get her to use paper, it's to make the job of cleaning mistakes up easier. Because the real job is to get her to hold it until she's outside. Don't reward her for using paper. Don't punish her for not using paper. The paper should be totally neutral - it's only there in the event she wants to use it. Rewards and happy associations should be made with going outside only. All inside elimination should remain NEUTRAL unless you catch her in the act, then scoop her up with a "naughty naughty" and hustle her outside. etc..etc... Don't make the "naughty" stuff extreme but make it surprising to her!
NEVER say anything to her about any mistake you don't SEE her committing. When you're home, watch her EVERY SECOND, or put her in her bathroom. She should HARDLY EVER be in her bathroom while you're home. Better to carry her in one of those front papoose baby holders than let her run around pishing in the house. Let her sleep with you and wake up if she's stirring and take her out. Only a seriously confused puppy (or one with a seriously inattentive owner) will pee in the bed. In 40 years of training puppies I've never had one pee in my bed. Large breed pups can be tied to the bed on a short leash if one is a light sleeper - but a Yorkie will do best in your bed.
Finally, teach her to fetch a toy. For some ungodly reason - once puppies are fetching well - they almost always finish their housebreaking quickly.
By the time she's six months - she'll get it. UNLESS you've psychologically infantilized her.
Good Luck!
