My 4-year-old is 43 lbs and my 7-year-old is maybe 47, so your girl isn't too mini. She's a nice standard weight for a female. She will stop growing in height around a year or so, and then spend another year or two growing into her bones. It depends on the genetics of what's in her pedigree, at least partly. It seems like the smaller ones finish growing more quickly than the bigger ones, at least in terms of maturity.