"I joined the knights when I was 8 years old."
... At 8 years old she could become a page, but not a knight.
Then after reaching 14 years old, she could be promoted as a squire.
And only after finishing her training as a knights apprentice, she could become a knight.
It might look that I'm just nitpicking, but a knight was not just a word to describe a simple soldier in plate armor.
Oh well, whatever, never mind~