You're quite tiny, cause I'm 13 and I'm 5'8", 164.6lbs. Try Half-Back or Wide Receiver.
Cheerleader.
Defensive tackle
Bench Warmer
RunningBack
fullback?
offensive line man at that age and size then as you get older if you stay around the same size move to defensive back
If your fast: cornerback or wide receiver
Defensive tackle.
Anyone you choose! - Most coaches would have you on the line
Punter or placekicker. No speed required.
In 7th grade you would probably be an offensive or defensive lineman.
cornerback or safety