How long will my penis be?

im always getting really annoyed about how kids who are much smaller than me are saying that they are bigger down there. also with armpit hair. i have none but kids smaller than me have em too. i have a good amount of pubes and a **** load of arm and leg hair.i really need help because i wanna know how big i will be. kids make fun of me and stuff b/c they can tell. im 5' 3" and have a 2" penis at rest and 3.5" erect.so can someone please hep me my dad and bros are big and how long does a kids penis grow when hes done with puberty.