When the women you've been with said that it was big, they weren't liars at all. Everything is relative. If they've been with average guys or anything below your size before they met you, then obviously it's big. Same would count for if your dick was smaller. What is big? There's so many variations. There's the statistics, there's the female, there's YOU, and there's the "competition".
Come on, use your mind, if you're going to a "large penis support group", that wouldn't mean they will be just "large", it will mean, the biggest of all dicks will be registered here, to communicate, work out issues, etc etc the list goes on.
In my opinion you are big, though I don't know your girth. In the end, the only one you need to satisfy is yourself, the women are already pleased, and who gives a fuck if this board is bigger than you? Like it's some kind of blessing... They just got born that way... oh well.
It's not advisable to look through all the huge cock things here, or in porn where they have all the huge cocks, for that matter. It will give you a very wrong view about that the whole world must have huge dongs, and that you're some kind of freaky exception. If anything, the opposite is true. No offense to huge guys, but it's just that when i hear a guy talk about his 7,8,9 inch GIRTH, that i consider him in the same category as a 7 feet tall man or such. It's just gigantism but then downstairs.
Man, work on yourself, the rest will follow. Don't worry about your dick when it's average or above average. Average means that of the 3 billion men on earth, MOST of them will have that size. Don't forget that a large percentage also makes up for what's lower than average. So all in all in the world, there's not much huge dicks.
For a realistic average, and not the strange advertising claims, read this:
Average penis size – What is the Average Penis Size
Good luck