What do you mean that you have a big dick, but it's small by this forum's standards? It's a fairy accepted fact that average is a little over 5 inches. So, if you're 6 or more then you are above average. I don't think you get into the "big" range until you're over 8.
Sheesh. That requires math and averages. I've been doing it for more than 40 years, but only 40 years of actually orgasming. Averaging about 5 times a week. (Sometimes more, but it's a 40 year average) my math gives me 10,400 loads shot. Glad it doesn't run out!
The average amount of cum someone shoots is about 1 teaspoon, so 10,400 teaspoons is like 52 litres or 14 gallons. Fun!