Sean is right, it's never to late to play football. I started in 7th grade and I made A team starting linebacker, kick off, kick return, and field goal block. I was scared that I wouldn't learn all the plays but it really is easy. I agree with Sean with linebacker, just don't be afraid to hit, think of something that makes you mad during the games, and respect the coaches and show that you want to play, they care more about that then anything
It's never too late to play. The question is what is your goal. Are you expecting to play in college? If so, it is going to be very tough, but it can be done. You will have to work and study extremely hard to develop football skill and knowledge. Your position is less about you height and weight, and more about you atheletic ability. Find a good coach and get the answers you are looking for. Then determine whether you have the time and dedication to make it happen.
It's never to late. Your team needs as many players as it can get. I don't know what you look like but I'd say you should be a running back or a line backer.