you're not alone. i never get wet from sexual arousal. ever. it's pretty ridiculous. the only times i ever get wet are completely random times when i'm not even thinking about sex, then all of a sudden my pants are soaked through. how annoying.
rest assured you aren't alone. everyone's different, some people just dont produce much lubrication. it could be your birth control, but it might just be the way you are. if you are feeling dry during sex, get out the lube.