Allow me to correct some of you lads about what a loli is:

Lavender is not a Loli, and neither is Gentian. I hardly doubt Lavender is even a Teen. She is what some rude people would call Loli-baba - a fully grown up woman with the looks of a young girl.
Gentian is not a loli either - she is a girl in her teens, maybe slightly more towards that adulthood.

Young looks are not the only factor that make a girl become a Loli. It is first and foremost the age. Both physical and mental. Lolis are also portraid with a peculiar set of facial features, such as slightly more chubby cheeks and such. Good example from the current pool are Daisy and Nerine. Those ARE lolis.

Also to add a little bit of detailed imput, you can watch this video. (Youtuber: Animeman, topic: What is a Loli")
https://www.youtube.com/watch?v=UP80nZOPk88