I suppose mine falls under the average category. But, guys always tell me I have a really nice cock. So, I guess it's ok.
I'd say I'm pretty "average" at 7"c and fairly thick, and never had any complaints. My wife's boyfriend is considerably larger at 8.5"c and THICK. I can totally understand why she likes his big cock
While in your situation, that seems perfectly normal, "Size" in itself doesn't necessarily determine being a top or bottom. I'm 7"c and fairly thick, yet like you, I'm a total bottom. Could I probably top another guy with my 7"? Sure... But I've always been a bottom, and topping another guy just isn't an option for me