Shih Tzu Yorkie Mix looking to breed

Breed: Yorkshire Terrier
Location: Southern Missouri
Date of Birth: 24 February 2018
Age: 8 years, 4 months, 14 days
Bitch (female)
Pedigree: No

Details:

I am looking for another dog that is 4lbs or less to breed with Hayden. Hayden is only 3.5 lbs and I want to make sure her puppies are not too big for her body.