To help some confusion, I just want to set her ages through the years mainly and then a few others.

Alysanne
-Born in the spring of 113
-In 124 she is 11 (chapters 1-3)
-In 127 she is just turning 14 (chapter 4)
-In 128 she is 15 (chapter 5)
-In 129 she is 16 (chapter 5)
-In 130 she is 17 (chapters 6-10)

Aemond
-Born in 110 AC

Jace
One year older than Alysanne

Luke
One year younger than Alysanne

Joffrey
11 years younger than Alysanne

Aegon II
6 years older than Alysanne

Helaena
4 years older than Alysanne