I’m 30. Been stuttering since I was 6 — however, from that age until about 16, it was pretty mild/moderate. Suddenly progressed to severe (like Ken Pile in “A Fish Called Wanda” severe) from 16 onwards. Tried speech therapy during high school from two different speech pathologists years apart. It has never worked for me at all. I may be able to occasionally replicate the breathing and enunciation techniques within the controlled clinical setting, but it all becomes futile outside of it in the real world.