I aquired my stutter or stammer in my adolescence. It was hell for me, people didnt unterstand, i didnt understand. I was extremly self conscious about it and tried to control it, reality is that it may have made it even worse and was no way to lvfe. It was just to exhausting. My advice is pretty hard: Try to come to terms with the idea that you will stammer your whole life and you cant really do anything about it. Dont cling to the fantasy that with the right method you can control your stutter. The fact that you werent a stammerer as a child is not really relevant to your current situation. If you can accept your stutter you can work on improving your symptons.