I want to know where she got the 3lb shih-tzu. I have never heard of them being that small. You had better hope that this pregnacy and or delivery doesn't kill her. I would have her at the vet now having those pups aborted and the bitch spayed.
Even breeders who breed for tiny toys don't usually breed females under 5 pounds! This female (if real) is very small for breeding. If you insist on taking such chances and risking your female by continuing this pregnancy, please do the right thing and seek advice from your veterinarian right away and establish some sort of plan for pregnancy, delivery and caring for the pups. This pregnancy and everything that goes with it (good or bad) is your responsibility and you owe it to her to do what's right.