I have a not severe (as you described) but also not a mild stutter. It's more in the middle and can vary from day to day and hour to hour, minute to minute ect ect. I have blocks on nearly every sound I can make with no predictable pattern.. it's just chaotic. And it's bullshit and it sucks.  That said, the difference between what I do and what you do is that for me is really really sucks. And for you it really really really really really sucks.  For what it's worth, I'm really sorry. It's not a pleasant experience.