Why I cum so little?

I know I have a small dick, and I'm fine with that (I like it that way). But, I have some decent balls.

However, when I cum, I do so in a very small amount, when I'm really aroused I squirt a few shots more, but still it is a low volume, and very diluted/liquid.

I'm really impressed with other men (real men) that when they cum it's not only dense/thick but in amounts that I would need to cum twenty or more times than me.

How could that be? ;)