you're right about average bro, you got nothing to worry about! you've still got time to grow as well, so don't worry about trying to increase the size. The only real way to do that is surgery and I don't think you want to be going through that at 16. A girl should like you for you, not your penis size.
Lol size is good, but its not always great. ex. Almost any girl wud choose a guy w/ small junk who knows how to use it and make it flawless verses a guy w/ big junk that just likes to jab it hard in missionary...
Don't worry about it dude you are still growing.