Huge cock you got already mate! are you sure you've never done pe? looks like some skin stretch at the base, but I could be seeing stuff .... dont take that as an attack, just such a big dick you got.
I would guess its approx 8-8.2 inches BP length and 6.2 inches or so in girth. Its around 1.75 inches width I would say.
You got what many guys here dream about, so you already have a large advantage to gain big ... if I'm correct and you are at least 8 inches BP than a gain of 2 inches length gets you into two digits!!!!
I know the black's are bigger is a myth but when guys like you appear it does make the uneducated revert back to it.