I personally stutter a little when alone, and stutter alot when in a group of friends or work team meeting and with the help of my psychiatrist we have narrowed the gap significantly. He never told me but he has recorded all the sessions we had during the past 7 months and said that I stutter significantly less than 5 months ago. Based on my experience, the key element for getting better is not to care about your stutter anymore. If you reach a level in your mind that you become friend with your stutter, is the moment that you wont focus on what people think if you stutter, and you dont care if you stutter or not, and after some months you may maintain the same level of stutter but never notice it, so when you reach this level your stutter gets better on its own, but you dont care anymore because doesnt bother you again. Unfortunately more you focus on your stutter, words and sentences, your social anxiety gets worsened, which results in even more stutter. A psychiatrist works on your fears and social anxiety and helps you to fix them.