My size...i know another one but pls read?

hi guys im at uni and im a bit weary of having atm due to my size. Im not sure if its big and im not sure if its small. i have nothing to compare it with. and dont say cos those guys are stallions on heat with steroids for good measure! all i want to do is to be good enough to please the girls and have a good sense that im not a joke to a girl and that my size is enough to satisfy her and more.