it is like feet, most people have one that is larger and sometimes a different size
16 is probably too young because they can change
but enlargement does not have to be overtly noticeable, and PERSONALLY "tear drop" look best and SILICONE is the way to go.
And if u ever wondered if they can "break easy"
there r demonstrations where they smash it with a baseball bat multiple times and no leakage.
If u get em; LISTEN carefully when Dr. says to play with them daily for a while to prevent scar tissue; it means REALLY PLAY WITH THEM; give a nightly test dr BECAUSE highly unlikely anyone is going to smash a baseball bat into one but watch the video and feel secure they won't brake.
good luck