I am not happy with my size

If you've looked at the stats and know that you're above average, then it's clear your problem is between your ears, not below your belt. I wonder if you're another victim of the unrealistic standards of "normality" as depicted in porn.

If you're determined to get a surgical enlargement, I suggest you look into this very carefully. It's not something I've investigated in depth, but my understanding is that the procedures currently available are risky and don't necessarily have the results advertised.

Even if the surgery did result in an increase in the size of your penis, I have to wonder if your penis will ever be big enough to satisfy you. Michael Jackson had a thing about his nose being too big, and look where that ended up. Some women get fixated on having bigger breasts and end up looking grotesque after multiple bouts of surgery with ever-larger implants.

You say you're convinced that you can't satisfy your partner. Given what you say, I doubt if you're open to rational arguments against you trying to enlarge your penis. I also don't know if you're gay or straight. However, assuming you're straight, I'll just mention that numerous surveys have found that only around 20% of women can reach orgasm through penetrative sex alone. It is true that some women are into big penises, but surveys also show that the vast majority are fine with average, and there are many other things about guys which they consider more important when it comes to sex.

"The guy downstairs"

Compare yourself with your national average.

I personally wouldn't risk it. Especially if you're above average. It's probably not your dick but you that's affecting your sex life.

It's not about size it's about what you do with it. You need to stop comparing yourself to other people and enjoy what you've got. Surgery sounds like an unnecessary risk imo, if anything went wrong you might never have sex again.