I'm the opposite. Girth comes to me before length. I've gained maybe a half inch or so too, over about a year of off and on jelqing and hanging. I have an extender but I never use it, I've gotten really consistent with pumping in a tube that's 3" in diameter by 9" long. That realls seems to expand me girthwise. So only time will tell if there's an increase from it.
It is always based on each individual though, so who knows what you can gain. But you will gain if you stay consistent.