I can't even say 6 to 6.5. Mine are def. only 6 inches.
I'm not too sure if it is true when people say you arms will look bigger with small wrists. I think it makes me look more like a midget T-Rex (sadly I am short too).
You can't make them any bigger - not enough to matter anyway.
You can make them stronger! Towel chin-ups and deadlifts, my friend.
I wouldn't worry about it. You cant change your genetics.