My almost-ten pound Chocolate has had an easier time of it with her health than six pound Laurel. She is still a very little dog and I can easily pick her up and carry her when she gets tired.
I found that the feeding recommendations on the bags of dog food were inadequate for my puppies. They have high metabolisms and need more food.
Laurel: born 9/1/18, 7 lbs, my homegrown
Chocolate: born 10/4/18, 9.5 lbs, rescued from DV situation