Trying to control it is what's causing you to stutter. You can't speak consciously,you just gotta let it happen. Picturing trying to walk by consciously contracting each muscle in your leg, it wouldn't work. Do me a favour and the next time you're in school listen carefully to how your teacher speaks. I can almost guarantee you that they will hesitate, repeat stuff,say ehhhh and so on which is all the symptoms of someone with a stutter,yet you don't consider them a stutterer,why?cause it's normal but you monitor your speach. To get to the point you are trying to speak perfectly which is completely impossible and no one has ever done it.