Small dogs take longer to house train....some more than others.
Some yorkies are barkers. I have two...one barks and one does not. Maybe because his sister does all the barking for him.
I don't know.
Do you reward Abby when she doesn't bark? As in...she barks, you tell her her no bark...does she stop if only momentarily? That's the time to reward her...praising her verbally and with treats for her "good" behavior to your command.