I am 20 years old and have fasted since I was 10. Because my family discouraged my fasting when I was a nine year old, I asked our Islamic leader here what I should now do.
He wanted to know if I was referring to my ninth Hijri or ninth calendar year. In his opinion I do not need to make up any days I did not fast at that age. However, I do really want to be sure and so ask you.

When a girl has completed nine years and entered her tenth, the age of puberty – bulough– has been reached.
It is after this that Islamic duties become incumbent – wajib – so you do not have to make up for any days you did not fast before that.