Can i weight trainning when i'm young and short?

I am fifteen and half. I so skinny, 5.41ft heigh, 115 pound.i work out three time a week. Can I weight trainning, now. I comfusing, because somebody told mel; "you still young , you can't do it , it's can make you short and weight trainning just for 18+. You can play sport , that good for you". but i want muscle, sport can't make big muscle for me. please help me!