I hope that you reconsider your plans to breed her. #1 she sound awefully small, why would you want to chance loosing as she might have to also have an emergency c-section. #2 it sounds like you don't have any clue about breeding, etc...therefore you would really be dueing her an injustice. #3 You really need to do testing on both male and female for genetic defects #4 There are so many Yorkies out there being produced by puppymills that wind up in rescues because they are sick and/or have genetic defects.
There are many more reasons, but I recommend you have your baby spayed and enjoy her and just love her like a princess.
P.S. Spaying females early on in their life protects them against cancer
