Perhaps I have misunderstood the original post...but I thought it said that your 12 week old chi is being fed 1/2 the recommended amount of food daily..And you are asking if you should reduce her intake of food even more?
If I have correctly understood what you said, then please allow me to say that I would be concerned about putting a 12 week old puppy on a diet. Adult chis should be monitored regarding weight issues as it can create health issues, however a puppy who is still developing needs adequate nutrition. For a vet to categorize a 12 week old as a pound overweight is puzzling since her adult size/frame and weight is yet to be known.
"There’s no changing people, and we can’t even help people with whom we’re emotionally involved. Let them be, stop expecting things from people who cannot provide those things, and recognize that we can live happy, productive lives regardless of what others, even close relatives, are doing or saying."