This might sound nuts but hear me out. Have you tried stuttering on purpose? It’s a technique. Basically, before planning to speak, you decide that you are going to stutter on something. Like a sound you know is coming up. You plan to do it on purpose. The reason is, when you try to avoid all stuttering at all costs, you can end up making it so much more stressful for yourself. If you stutter on purpose, you are putting yourself in control of the stutter, not at the mercy of it. Also, there’s a technique called bouncing or bumpy speech. Again, you choose to make your speech bumpy, lightly bouncing on purpose. I hope this helps some.