Life long stutterer here. I would say I was on the level of non verbal when I was a kid as every word I spoke I stammered on. Now 40. I only stutter when I’m really nervous or mad. 99% fluency any other time. Went through a ton of speech therapy as a kid. It’s a waste of time and money. What made it worse was avoiding talking, what cured me was forcing myself to get a job that I had to speak to random people. With age came the “I just don’t care anymore” attitude and the second I stopped caring it went away.