After you got your first few armpit hairs, when did you start to rapidly grow more?

Okay so i have like 5 armpit hairs on each arm that you can actually see, but u really can only see them if you are very close. Its been this way for like 5 frickin months! It pisses me off. It seems like they just like stopped growing. So for those of you who have pit hair, after you got your first few, when did you really start to grow more? (I have pubes by the way, and definitely have started puberty)