With your size and with more growth in height to come, I would recommend a skill position like defensive back or wide receiver. Great NFL players like Steve Largent were not much taller than 5' 11'. Additionally, if your quick on your feet this in my opinion would be a great position to start. Other positions my also be consider would be field goal kicker. Keep in mind, a strong desire and heart to play will overcome many perceived considerations a coach my feel you are limited too.
RunningBack
the bench
fullback?
Kicker or waterboy
I would say wide receiver or cornerback
Anyone you choose! - Most coaches would have you on the line
Quarterback
running back
Linebacker. fullback.
Linebacker or Defenceve end
anything but defensive linemen
It depends on your age. If your 12-14 you should be a lineman, if your 15 or older you should be AA saftie