My yorkie just gave birth for the first time and she only had one, is this normal and how will I know if she has any more in there?? What will happen if she does not show destress and there are more puppies? What are the chances of this one puppy surviving as I'm doing all that is possible from my side. My husdband is at home with her and I'm away on business.. please help?

You really should have already had a shot of oxytocin at the ready.
When a dog 'finishes' whelping and you aren't 100% sure they are done breeders will give a shot of oxytocin which basically helps flush out the uterus and speeds along delivery of any remaining pups as well as cleans out any 'leftover' material.

One puppy is pretty normal for a first litter, especially with a small breed dog but if you have any doubts at all as to whether there are more pups and it has been 2 hours or more get her into the vet.