It’s about mindset. Have you noticed that when you talk to yourself being alone, you probably don’t stutter. It means you don’t have physical problem, it’s only mental. This “mental problem “ activates when you are with people which in turn causes a physical difficulty getting the words out. My fluency has improved a lot but sadly I can’t say what has caused that. Many things combined. But I think my turning point was finding out about William D.Parry- his videos on YouTube- he has an interesting explanation what happens to us. How has it been if you told them that you are stuttering?