I agree. Most women prefer their guys not so hairy. So consider yourself lucky. And 5 inches is the industry standard, I believe, even though most will say they have 10 if you ask them. ;-)
PS:
No hormones will not makae your penis grow larger, but it could worsen your pit hair problem, as well as give you other problems.
I think you should feel lucky that you don't have an abundance of underarm hair.
As far as your penis, people make do with what they have.
What you state is more than enough.
Good luck!
--Rad