I’ve clamped about six months pretty steadily after a year or so of newbie routing. I built up to 10x10x10 sessions erect. I have had no measurable girth gains. It’s very frustrating.
Time to change your routine mate. De-con break maybe. They say doing the same thing over and over and expecting different results is a definition of madness. We’ve all been there. Take some time off and come back in a couple of months and do some simple jelqing. Good luck.