I think you should try clamping, without the clamp by substituting it with a latex cockring, it cuts out all the injuries and gives you the full expansion from an erection which works the tunica etc.
I remember the first day i ever did this kind of clamping, i gained .2mm in glans size, and it wasnt temporary.
You will know you are doing it right when you feel a kind of urinating feeling in the glans.
This shit reall works, cos i have to switch sides when clamping, it works so great that one side of my penis grows faster than the other, so i clamp and train the other side the next time i clamp, one day on and one day off and on alternate sides.
you cockring is only used to achieve maximum erection and expansion possible, but that is only half of the process.
Next, you must edge, by masturbating, and hold back from cumming 3-5 times within a 30 minute high strenghth erection.
Its a bit like a priapism and the gains are out of this world, i can bet my house you could gain another inch in girth with this, give it a try.