Balls don't 'Drop'
where would they go, onto the street? They just hang there, suspended in the scrotum, where it's cooler and they make sperm better.
As you go thru puberty, the testes get bigger. If your testes are still small, then you haven't gotten that far into puberty. Not to worry, eventually you will, and they'll grow. Like everything else on you. Until then, don't worry yourself about it too much.