First you live in the Phillipines, I'm not sure what your country's dog registry rules are. But if you wanted to register any puppies with AKC, those puppies could only be registered if they are purebred. And the AKC would need to recognize your country's kennel club, and the purebred parents of those puppies need to be registered with your country's kennel club. That information can be found on
www.akc.org No reputable registry will recognize a cross bred dog, for conformation showing. That is two dogs of different breeds bred together.
A google search for dog registry in your country has yielded the following:
AKCUPI » Articles It looks like relatively recently it got FCI accreditation.
In terms of health issues in female dogs being avoided if they have been bred, I'd like to point out that your personal observations are by the very fact they are personal quite limited in scope. For more objective observations go to the research that has been done.
The parent club for the Yorkshire Terrier in the United States, does NOT recommend breeding of any female under five pounds. Go to
www.ytca.org
I understand that different countries might have different ethical practices; and as such I think you would have a clearer and more informed answer, if you asked your questions with you country's National Yorkshire Terrier Club; and or go to your country' s National registry.