You are making a (hopefully) fifteen year commitment to this puppy so make sure you are prepared. They are like infants for the first year with sleepless nights, having to puppy proof you house, etc. I don't know how old you are, but a dog does tie you down. You can't just pick up and go whenever you feel like it anymore.
A dog is a huge financial responsibility, too. Have you considered that? The first year is expensive and as they age they tend to really rack up the vet bills. Here is a good article on the cost of owning a dog:
The Cost of Owning a Dog
Hopefully you have already considered all this and will be a great Yorkie mom!