Re: should i
Just go the gym and ask a trainer to develop a plan for you. Unless your overly developed heavy weights are not recommended until 16years of age.
You will basically get a workout comprising of body weight stuff as well as endurance training, IE: 15-20 reps of a low weight
This will build up your strength but won't make much bulk. You have to even be careful doing stuff like that.
As I said just go to the gym and ask a trainer to make a program for you, and he/she will go through everything with you.