Puberty??!?

just turned 16 in mid april and it seems like my still hasnt grown at all even though i have pubes, underarm hair, acne, and ive just started to get facial hair and some on my stomach. pretty much everythin is there or is happenin except for my voice changin and growth. my is only 4 1/2 inches and im startin to get real worried that i could be screwed. please help why is everything else in puberty working except for my growing???!!!