The website posted a few comments back is actually very informative and scientific. Talks about how to measure properly both length and girth, how porn uses perspective to skew things, how body size matters etc.
For instance, I always assumed I was small. Turns out I am 1.26x average! But because I am a large guy (6'2", 290 lbs) my penis appears small to me.
But when measured using the scientific means laid out in the site, I am not small, I am exactly 6" with a 5" girth.
My problem is that my belly gets in the way and prevents me enjoying some positions, and I have a fat pad around the base which makes it appear smaller, but compresses during sex and apparently "bone pressing" is the correct way to measure. I thought I was cheating!!
All the more motivation for me to keep losing weight and looking after myself. I am down 28 lbs since I started hobbying 3 months ago and now that I know my dick will get bigger as I lose weight, Im gonna be at the gym every day