Speech therapy differs. If you haven't had success so far, try a different speech therapist. In this subreddit, I've read members describe therapy that made me cringe. I had a severe stutter from early childhood until my 20s. Speech therapy did wonders for me in my 20s. I had seen speech therapists in school and such prior to that, with no improvement. I'm a huge advocate of speech therapy. If it hasn't worked for you already, it doesn't mean that it can't work for you.