I have five furbabies, weights range from 3.9lbs to 6.2 lbs. All of my babies are healthy and energetic.
Might, who is the 3.9 pounder, is the most fiesty one of the bunch, he runs and jumps all the time, I haven't had any health problems with him and he just turned 6 this past October.
Miko and Prissie are 4.5 lbs, and were my breeding babies, they had 2 successful litters, she miscarried her last litter in October. She came through it fine and that was the end of my breeding career, she is set to be spayed in the next couple of weeks. All her puppies with the exception of one, have an adult weight of 3.5 lbs. and are all healthy. I keep in touch with all of them, YTer Layla's Mom, is mommy to one of my grandbabies. Max, Layla's littermate, stayed with me, is the 6.2 pounder, not sure how he got to be so big, but it happens and he is a joy to have.
Kylie is my other 6 pounder, however when you look at her you wouldn't think she weighs that much, she is as compact as Might, 3.9 lbs, but she is just a little thicker.