yorkies are just notorious for having a hard time potty training. you seem like you're doing it all ok to me. just keep at it. and like my aunt always told me. if your eyes are not going to be glued to the dog they need to be in the crate. we used the crate at home for a fast place to put them when we were busy cleaning, cooking, working, and we used a larger excersize pen for day times while we were gone more than an hour for more space with pee pads for a place to go in case.
also teaching a puppy to ring a service bell helps them learn to tell you it's time to go outside. just set a bell by the door you always use and tap their paw onto the bell and say "OUTSIDE" and then take them out, if they go treat and reward, if not say nothing. doing this everytime you go out for potty they learn to tell you it's time rather than you having to pay attention all the time.
good luck