Most of what I would recommend has already been said, but I have a few things to throw in. Why is this puppy NOT registered? You said the parents were. Were they registered AKC or one of the less reputable registries? You mentioned CKC -- I would NEVER breed a CKC pup. Was the puppy not registered due to a problem knowing which sire mated? Is the pup just given limited registration and you are not supposed to breed her? Was there some other issue that made the breeder decide NOT to register the litter? Do the parents both meet the
AKC yorkshire Terrier Breed Standards? What about the grandparents on each side? What is the health history of these 7 dogs (including your pup) AND all litters from them that you know of or can find out? Genetics will involve more than just the 2 dogs you breed. If you go back to their parents and grandparents, as well as looking at other puppies from their litters you can get a good idea of what you are dealing with as far as characteristics and health concerns. You want to ask specifically about things like liver shunts and LP (joint problems) which are prevalent in yorkies.
I do NOT recommend she be bred as she is NOT registered. No reputable owner of a registered male who meets the standards is going to allow you access. I am interested in her history and the questions I brought up previously.
I also do NOT recommend you breed this girl because breeding just to have one litter is not a good idea. So much study and dedication is involved to do it right, rarely does that happen for just one litter. You are not going to make any money on the first litter if you do it right. There are just too many expenses, including your own library of reference material, all of the pre-mating testing, CHIC certifications, xrays, blood work, vet exams, whelping kit/box/materials, medications, special foods, etc.....
I also do NOT recommend you breed her because if she is already 7 pounds, chances are very great that she will go over the breed standard of "not over 7 pounds." Some may stop growing at 8 months but most will continue to fill out a little over the next 10 months. The main body composition may be there but they do usually add some girth. If she were to only go over the weight standard by a little (and that was the only standard she was missing), that would not be that bad of a thing -- again, look at the whole family on both sides when thinking size. Even a 5 pound dam with a family history of overly-large pups, should not be considered a good breeding candidate.
You said she was a little on the long-bodied side. Yorkies should be more "square" -- only as long as they are tall. If that were the only thing wrong and all other things were optimum, you could possibly find a male with a family history of shorter-bodied pups to breed with her. But again, I cannot imagine any respectable breeder allowing her sire to breed a non-registered female with an inexperienced owner.
My next question is about your own history -- You said you have had 6 dogs in your 20 years. What happened to all of them? Do you still have them all? Are you speaking YOU had these 6 dogs during your responsible years or were those from your parents during your whole lifetime?
I lost a female on the 3rd day after she gave birth to a litter. Her puppies were all born healthy and perfect. She was registered AKC, within standards, a beautiful, sweet girl who I loved and planned to keep forever. I had studied over 2 years, was well-prepared, had plenty of money set aside for emergencies, and did not plan to or need to make any money from her puppies. I was most interested in trying to breed that "perfect yorkie" that would epitomize the breed standard. I should have been content that someone else had already done that and my 2 yorkies were just perfect for me. I cannot tell you the horrible guilt I feel for having bred her, knowing she would be here with us today, if I had not. If you cannot separate your beloved pet from a breeding dam, I would NOT take the chance. Even the best prepared sometimes come up against an accident they cannot control. But I am haunted by the fact that had I known a little more, been quicker to act, had a mentor with me, I could have prevented her death. Leave breeding to the experts. Unless you decide to become one, do not risk the life of your precious girl.
If you do decide to become one of those expert breeders, the
first thing is to make yourself as knowledgeable about yorkies, breeding and dog health as you can. Then, the
next step is to find a reputable AKC breeder who has shown her dogs so they have been evaluated by unbiased judges. Ensure she is knowledgeable, experienced, reputable, ethical and LOVES her dogs. Make sure she is willing to be accessible to you for expert advice. Ask her if she would be willing to be your
mentor for breeding when the time comes. Once you know you have found the right breeder,
THEN you look for the right pup with your mentor's help. Ensure she is AKC registered, from great lines. You will not know if she is breeding potential until about 8 months old. Some say 6, some say 12 months. I am giving you a happy medium.
Then when you have decided, and had at least 2 experts agree that she is breed standard and breeding quality, you can start your search for the complimentary male. You are going to have to have a detailed analysis of your dog's physical characteristics. Then you need to learn the basics of genetics to know how to compliment those characteristics with a male. Some things are simple with a trait being dominant or recessive. Some traits are a combination of genetic markers and it can get very complicated. Best to ask for advice and also best to stick with 2 dogs that are all within the standard. That way no matter whose traits the puppies wind up with -- they are still within standard themselves.