the difference between 4.5 and 5.0 inches wouldn't mean a dang thing if i loved the guy. probably 90% of women don't get orgasms from penis-in-vagina penetration only (there's got to be some external clitoral stimulation for most women to have an orgasm).
so here's my point. throw away your ruler. consider it defective or whatever you need to do just to forget these measurements. you'll probably meet some real nice girl who's seen 2 or 3 penis' in real life and all of them would have probably been close enough to yours in size that unless she took out a ruler, she'd never know the difference.
here's some final, parting advice. 1) relax. 2) learn how to use your penis, your body, your hands, your fingers, and especially your tongue.
if you do those 2 things, you'll never have a problem making a woman plenty happy. trust me. i know.
jasmine