My life is very similar as yours, I stutter since when i was 4, did speech therapy for 8 years (helped me a lot going throughout high school) but when i finished high school everything changes, the old me in high school died and now it's a person who is afraid do talk, avoid talking, avoid eye contact. I am so ashamed of myself that I can't even say "Thank you" or other greetings because is a big effort to say and I don't want to stay with my mouth open trying to produce a sound. People think I am rude because I don't say good bye or the little chat the cashier always have with you.