It's not all that grim. Don't worry, I stutter (ed) the same way. Don't place to much weight on speech therapists. You have to take a moment to slow down and "feel" the block that is arising (for me it's in my throat, but can be lower in your abdomen or more in your head like a lot of racing thoughts) & "dissolve" it with breathing/positive reflexive thinking & I'm sure there are other ways as well. Chat with me and I'll share a couple of videos that helped me, maybe they do something for you✌️& it's not genetic. It's just a reflexive response we have created, primarily in our heads that leads to physical blocking of the body not allowing the words to come out.