Why is finding someone to date so hard and am i behind the "Curve"?

i'm 21 ive only have had with 2 women didn't go to prom,never had a gf, never had a valentine nor have i ever been on a date. i just feel so behind like most people my age have had relationships been in love all the little things and i never have, like most of the girls i like never like me or when i do get to know them they just don't seem to have anything going on. i don't know whats wrong but i just feel so far behind considering im in college and these are supposed to be your wild promiscuous years but yet strangely enough i can't even seem to get off of the "ground". i have a great personality, im tall and well build i think im easy on the eyes but yet i no one i find likes me and the girls seemingly treat me like i don't exist what can i do?