I was the same way in Highschool and even a little while after...almost all my friends were guys, especially since one of my primary hobbies was gaming. I didn't start making female friends until I started working as a pet groomer and was working primarily around other women. Being stuck in a fishbowl at a petsmart kind of forces you to at least try to get along with your co-workers.

One thing Ive notices is girls seem to think you're slutty if youre hanging out with guy-friends all the time. Its like they think youre sleeping with them all or something...cause you totally cant just be friends with the opposite sex, AMIRITE??

The only real bit of advice I could give is get involved with some sort of an activity thats pre-dominately women. I'm sure once they actually get to know you then you'll make lots of female friends.