I am 16 years old and I have a lot more body hair than my dad. He just has a love-tail and lots of chest hair. I have a love-tail that goes up to and around my belly button and connects to the chest hair and spread across my stomach. Each of my chest hairs are a little over an inch, my dad's a little less. I can't even tell where my pubic hair really begins or not since I have almost 4 inches and since it grows up to my stomach there's no difference. I have hair on the shaft of my penis is growing almost up to the halfway point. How long is the longest chest hair, pubic hair, and armpit hair can you get? I bet when I am done growing that will be me.
It is the distribution of hair and not the length of hair that indicates whether you are done growing or not. From your description of yourself, you have reached stage 5, which means you are done growing in height. You can double check this by using the Tanner Stage Calculator for Boys which asks about more signs of development than just hair distribution.
The length of your hairs is controlled by the cycling of each hair follicle. A hair follicle will spend months in the "on" stage growing a hair. It will then go to sleep for a month and during that time the hair will break off. It then wakes back up and starts producing more hair. Since you have thousands of hair follicles and each one runs independently, you never notice when the follicles go to sleep, other than you will find a few hairs in the tub each time you bathe.
It is the on-off cycle that controls how long a hair will get before it is lost. The hairs on your head have long on times. The hairs on your arms and legs have much shorter times. The hairs on your chest are a bit longer. And the hairs under your arms and on your groin are longer still, but not as long as the hairs on your head. The actual lengths for any individual varies by genetics.