Hi friend, my case is the opposite of yours, I want circumference and when I asked the same question as you (but opposite) I was answered that I should stop the exercises for length and focus only on circumference.
I need to tell you that in my case (and in some others that I interacted with here on the forum) gaining thickness/girth is much more complex.
I used the extender and you are on the right track, 6 hrs a day on the extender minimum, control the traction always and if possible stay as much as you can with a penis sleeve when you don’t have the extender, so you can keep your penis stretched out and forces it to regenerate like that.