Your options are to seek professional help or to realize the deleterious affects of your actions.  It appears to be turning into an unhealthy obsession and you must take control. You are the captain of your ship and if your behavior does not change there are no good consequences that will come from your obesessive behavior.  Occassional, self-gratification is actually normal but when it begins to consume your time and keep you from doing constructive things, that you know you MUST do (like school), then you are obsessed and you have a problem that needs to be resolved.  Get a handle on it (excuse the pun) or you will find yourself in MAJOR trouble because of it ... You're 18 and at the doorstep of manhood.  You have to be more responsible.