hey, im 21year old man, i have question about penis size, im 8,3cm (3,26 inch) fully erect (i measured it with ruler on top of the penis and pressing the rule hard against the pubic bone) when flaccid 3,5-4cm (1,4-1,6 inch). Do i have to be worried about my size, is it still normal?Is there anything that i could do to increase my size?