Can rough masturbation eventually decrease penis size? Am I screwed?

Definitely can. Your penis will eventually break down from constant abuse. I used to masturbate for hours using only spit; I now suffer from a swollen penis head. My penis head is sore to the touch and discolored. I used to have severe OCD as well; it tormented me throughout my teenage years and made me feel as if I was crazy.

 

Answering the title question, YES.
It's already proved that excessive masturbation weakens it, make the blood flow not enough to reach the full size and it deplets the body from essential nutrients used to manage testosterone levels.

Now about the second question i can't answer because i personally never suffered from that sort of situation althought there are stories about other rebooters saying that the erection quality is renewed to the normal again.

 

As i said, there are rebooters that confirmed the damage was reversible. How much time till it happens? I don't know, you might try and see if it works.
And don't forget the basics, any concern that is definitely overwhelming you, talk to a doctor

 

Yea it definitely retracts after too much mo. I’ve always noticed it turtles up for a few weeks while you reframe from using it. But after about 3 weeks no mo it soon starts hanging better and gets more engorged. I worried the same thing as a young man as it really turtled up. I became obsessed about it. But nearly every young man/teenager has bashed the hell out of it growing up. It just needs a rest. You can take supplements like garlic tablets, ginkgo bilopar, Zma. They’re not miracle cures and most of it is in your head obsessing about it can put you in fight or flight and it will naturally shrivel up. Get a pump or a penimaster pro if you’re really insecure will add about an inch with a lot of use. And moisturise it a bit but be careful with this bit as you might get triggerex

 

6 foot tall here. 4 1/2 inches fully erect. And often very small flaccid with small / tight balls. I'm pretty damn sure that excessive masturbation is partly why my penis is so small. I did not death grip too bad, but was heavy on the downstroke, which I suspect made it shorter.

Reversible? I've heard yes and no from others on here. Mine has stayed small, but sometimes I have a better looking flaccid and fuller balls. That's something, isn't it?

Also - if masturbation made it smaller, then not masturbating will at least stop making it smaller.