you dont need to credit me for the tutoria, but ill say that its great youve learned so much from it, its a real compliment.
pleasentry's aside, i think the arms look fine, the problem is actually the torso, it is quite V shaped from the belt, and isnt too defined, try thinking that, when you look at gohans torso (or anyone elses). from the bottom of the waist, it will go almost straight up, and then outward after a time, as the lat muscles take effect on the shape. i suggest dropping the belt a bit, itll give the slender appearance which you need for gohan.
another good way to check your polycount as you go, is to press '7' itll put the count for whichever tool your using in the top left of the viewport