You’ll have a hard time gaining length with this size cylinder. The diameter of it gives you a lot of room for girth expansion, if you wanted length from pumping you should have gone for 1.5” cylinder, then you would have been able to pack the tube girth wise more easily and as a result get a better length stretch.
Do you do any stretches for length?
Maybe try to go for the combined approach, so you’ll do 5-7 minutes sets of jelqing and pumping one after the other.
I jelq in between my pumping sessions using a palm down grip, which moves a lot of blood and gives me a real big expansion, I do strong intense jelqs lasting about 3 seconds each.
Also incorporate some squeezes in those jelqing sessions: horses, sadsacks, uli’s, etc.
You haven’t mentioned squeezes so that means you don’t do them?