You are not at an age to think about your weight in numbers. Any numbers. As you grow, you'll put on some fat, then you'll use it to develop. You might get taller, you might develop muscle: you do NOT yet know what kind of adult you will be, so doing things by the numbers would take psychic ability you do NOT have!
What you do want to aim for is to be a fit and healthy young person, to lay the foundation for a lifetime of health. So. Try to eat healthy. Get your fruits and veggies, avoid as much "junk food" and fast food as you can. Choose reasonable portions, then go back for seconds if you're honestly still hungry. Go easy on the sweets.
And exercise *regularly*. Start small, maybe 30 minutes, but do it every day (take one day off per week if you want). A short bike ride, an easy jog, even a brisk walk: as long as it makes your heart pump a little and a bit of sweat break out, it counts! Work your way up from there. I think cycling is one of the best ways to get fit and burn fat. Just make sure that you're *working*: your legs should be spinning pretty quickly, about 90 rpm or one and a half full turns per second, so that your heart has to move blood and your knees don't blow out pushing against a heavy load!
You'll be strong, and fit, AND your body will develop with less excess fat than most of your peers! Can't beat that!