Yet another penis question?

I am 13 years old (14 in June), i'm quite tall and very athletic, and i was just wondering if my penis size could be predicted. A little while ago i measured my penis and it was 7 and a half inches long; i measured it again today and the girth had gotten bigger (i didn't measure it last time but i can see it has) and the length has increased by .2 of an inch. Can you predict my overall penis size so that i have an idea of what i'll end up with? Mabey use the amount grown and the time taken, idk.

Please, satisfy my curiosity :D