You need to start giving zero fucks. Really. When you talk to someone and you stutter, don't be mad or sad afterwards. Just keep your head up and try again. Sometimes you will fail badly, but you may find yourself being almost completely fluent sometimes because your brain doesn't have time to think "Oh, I will stutter". Go out of your comfort zone. Recently, I've begun to talk to people when I am at a party. And I can guarantee you, people thought that I was drunk when in reality I was just trying to be more happy, more talkative if that's a word, and just give zero fucks.