I used to stutter and my own younger sister would make fun of me. This was very depressing and even though I don't stutter anymore, it's a horrible memory that sticks with me. As for you: are you fat or do you over-eat? do you masturbate often? do you go to sleep late and wake up late when left on your own? If you answer yes to any of these, then you are contributing to your condition. Stammering/stuttering is usually preceded by or happens during a panic attack; so try going on runs to build your cardio as this will help with the panic attacks. Become goal-oriented and work on making yourself valuable. Don't define yourself by your insufficiencies or playing the victim card. God knows were all victims of our insufficiencies, apparent or not. Winners don't make excuses. By making yourself useful to those around you will boost your confidence.