See, this is why I don't like stages. The amount of body hair you have has little to do with how far you are in puberty and can't be measured like that.
So completely forget stages man. Next, masturbating doesn't speed up growth (why would it? You release semen...not hormones
You're probably just a hairy guy and your hair's coming in early. It's not abnormal at all - it's how puberty's going for you individually!