KittyCat,
My understanding of an extreme uli is this:
You are aiming the slow down the return of blood, while keeping the inflow of blood high. You do this with light clamping all around the shaft, but not too tight. If you clamp down too tight, you’re just doing a clamped uli.
So when you clamp down, you want to stop tightening when you’re at the stage where your unit is filling up more and more, until it’s at capacity. Then you keep it on for 10 minutes or so, perhaps kegeling.
So to answer your question, I don’t think it is ok for you to carry on as you are. The loss of feeling is a warning sign, heed it!