Personally, when I make a committment to adopt anything, be it human or animal, then I honor my committment and do whatever it takes to give that little life a fighting chance. I would never adopt a human baby and then throw up my hands should the baby get ill, and give it up again. I just wouldn't be able to live with myself. Same thing goes for an animal I've committed to adopt. Regardless of how much trouble it is, I would never give it up again.
If you really want to breed, I wouldn't do it with this little girl. She sounds too small and it takes so much out of these little dogs that she might not live through it. I would keep her strictly as a pet and eventually invest in another dog if you want to breed, and I wouldn't do it with a tiny. They are just too fragile. It would kill me if something were to happen to my baby. You should go for a larger Yorkie female dog and breed her with a smaller male if you want to try for small puppies.
I don't think you can go into buying these little pups just for profit purposes. You have to really love them, and
then you may want to breed. You should then learn as much as possible about breeding. Go the this website (
http://www.shooterdog.com/alexfaq.htm) and read what she says about breeding and educating yourself on it. It's not a walk in the park by any means. You'll find that the babies take a lot of work, and the new mother, being small, will need special care as well. You'd better be sure you want to put yourself through the wringer to do this. Yorkies aren't like other dogs when it comes to breeding. But your first motivation should be love for the dog, not love for the money you'll make. If you only love the money, then you may not have enough committment to go through what you have to to breed these dogs.