I am so happy to find this, as I find myself really similar to you, minus the self block. I never once block when speaking alone. I am 31, had speech block when I was 9 for about a year iirc, had it completely disappeared, then it came back around 2019. I mostly block on vowels, while consonant block come and go. Still, it only rarely happens, like 3/10 sentences . After moving to a country with different language, my blocks skyrocketed, like 8/10. I tried to be aware when the block sensation starts, also tried to speak with people at least once a day. It's getting better maybe 6/10. I'll try these things. One question tho, by "stop speaking to yourself" do you mean with voice? or just stop thinking to yourself altogether?