Hi bnasty,
Take a look at this book: Your brain on porn: Internet Pornography and the Emerging Science of Addiction.
It will give you deep review of how erections work in the brain. Mainly, your brain doesn’t know the difference between porn, imagination and real sex.. Try stop masturbation for a while. But it shouldn’t be a problem if you don’t over do it. The thing about porn is that in minutes you can see too many actress in different situations and each actress will make your brain understand her as a different sexual partner. If you “fuck” 3, 4 women every time, how it would be to have only one? Porn make us used to over stimulation. Once we are used to over stimulation, it becomes the new normal. First a playboy magazine was enough, then you need penetration videos, after a while you need different content, like orgies, pissing.. Simply because normal sex doesn’t get you aroused anymore.
Think in tunica as a very thin skin. If you are very fat and loses weight by stomach surgery, the belly skin is so stretched that it doesn’t come back anymore.. It’s how we have permanent gains in penis. All you have to do is grant enough blood to your new size. Nicholas’ advice is gold. Try some IC muscles exercises.
Hope it helps!