If she is only 30 days PG (barely) I believe it would be too early to hear heartbeats yet. Gosh, I would guess it's almost to early to even know for sure if she is PG. Have you taken her to the vet? They may be able to palpitate her belly to let you know for sure. Has she had any loss of appetite and/or morning sickness? That is one possible sign of pregnancy which lasts about a week. Their belly doesn't get really big until the last week or two before their due date. You should be feeding her a high quality puppy food during her entire pregnancy and even afterwards until the puppies are weaned.
It's great that you are reading up.....have you been to the debbie jensen website? I found it to be the best IMO. Lots of good information on every aspect of breeding from the heat cycles through weaning of the puppies.
Good luck to you and keep us posted on her progress.
BTW, coincendently, I have a yorkie named Halle also. She is only 8 months old and we are anxiously waiting for the day when she will be old enough to have puppies too.
