Penis size growth typically doesn't start until around 11-16 years of age (average: 13-14). Normal penis size covers a wide range, and the average size is probably smaller than you think: about 3 to 4 inches (about 9 cm) in a non-erect, mature male. As there are boys with penises larger (perhaps twice that size), there are also boys who have smaller, and still normal, sized penises. When you're an adult, you'll learn that size doesn't matter so much, but it still can be very frustrating! Try not to worry about it if you think you're "too small" -- appreciate what you have! If the other boys tease you, just say "heh, it's not the size that matters, it's what you do with it!"