I used almost exactly that same grip for a while. I also have short fingers and a big palm. I kind of subscribe to the theory that grip is just as much about the rest of the body as the grip itself for a lot of people since it sets the tone for what the body intends to do.
In general I've found that my grip and posture interact, which sometimes leads to "griplocks". When my grip isn't leveraged right through the wrist, I'm more likely to swing more "over the top" when I plant seeking more power/power transfer, leading to WTF Richards.
My current grip is still pretty close to yours, but changed a little bit to be slightly more like a modified power grip where my wrist seems to stay much easier to keep in leverage. It evolved that way after changing a few habits before throwing.
Hammers were a lot of it but of course the disc ergonomics are each a bit different. Sometimes I still do things like put the disc in my left hand and waggle it a bit and re-seat it in my right hand before throwing. This is a way of making the grip better by making it feel "new" to the right hand for the task each time (old motor learning trick):
or some of the old Blake T tricks kind of emphasizing "heaving" it more through the hit point but still with my whole body to make sure I'm leveraging it thru the wrist correctly. Over time this helped my grip(s) settle down. I really do think small differences can have big impacts here, especially once you start throwing faster (as I know you can).
When the leverage is right and posture is better, I'm much more likely to get early releases than grip locks (highly predictable at this point). I've started to use that as a kind of diagnostic for my own grips.
