I didn’t read through the whole thread. I sometimes use a similar masturbation technique using the same hand though. With the thumb on the top at the base and my fingers underneath. When I do this my head swells up a bit and the veins show a bit, but it deflates slightly when I release my thumb.
I was wondering does this mean I have a venous leakage?
I thought this was just because I was adding extra resistance to the return flow leaving my penis thus keeping more in it? I don’t have any trouble staying hard otherwise and still get morning wood and spontaneous erections.