1.
It is all NORMAL for a girl to reach puberty after 8 years of age.She would not be treated by a Peadiatrician (child specialist) anymore,because the doctors would consider her an adult.
Precocious puberty is the abnormal early puberty for which the age is 8 and before 8 years ,for girls.
2.
The marriage of Aisha r.a. was consummated at the age of nine years.( sahih Bukhari 5063)
3.
Aisha r.a. had herself mentioned that a female is a "woman" when she is nine years old.(Tirmizi 1109).It means she considers the girl to be an adult at this age,not child.
Her words simply imply that she was an adult female at the age of nine when her marriage was consummated.