If you are passionate about the breed and want to breed quality dogs and you have the support (vet & mentor) than you should do it.
The problem with dog overpopuation is not responsible breeders, but irresponsible backyard breeders and puppymills.
If more people bred for quality, not cranked out litters for profit, there would be much more healthy yorkies and dogs and not homeless ones in shelters.
So I do not see anything wrong with you wanting to be an ethical, responsible breeder. Please visit my page here to see info about looking for a breeder:
http://www.superpets.org/the_facts.html#breeder
(#1 wouldn't apply to you since you are just starting, yes, everyone has to start somewhere)
Best of luck in your endeavor to follow your dream!