If you are really worried about stunting your growth, just don't train too heavy, too often. Try, if possible to use no more than your body weight for resistance.
The reason for this is, at your age, your bones are growing. They do this by forming epiphyseal plates (growth plates) around the ends of your bones. Inside these plates, is a lattice of new bone formation, that is hollow and sponge-like, as all bones are. Only in these growth plates, the bone formation is not nearly as dense, and can be easily compressed, thus retarding bone growth.