Manual stretching is your best bet, since length is what you should be shooting for. Your girth is already way above average. If you don’t believe that, buy some standard sized condoms and some large sized condoms and compare. You’ll notice the large ones fit you much better. You’ll have some extra length left you don’t need to unroll, but that isn’t what matters. Condoms are sized by girth, and you are large.
Oops, I knew I left one part out. Actually my girth is 5 inches. Believe it or not, my girth actually used to be 6 inches, and 7.5 inches erect, back in high school. I pointed out in previous threads that I masturbated daily for two weeks in boarding school just to keep sane in an all-boys school, and my conscience was telling me that this was going to be a big mistake. All the other forum posters told me masturbation has no effect whatsoever. Someone even piped up and said that the way I was masturbating(briefs on, basically rubbing back and forth and side to side, basically masturbating face-down) is probably why. One website put it as too much excessive pressure on the penis, namely the base.