I'm never wet enough down there when it comes time for sex?

I swear, it doesn't matter how much foreplay we have. It seems like I get a little wet but never wet enough for him to enter me without having to use spit as lube or something. I'm only 20, and I should just be ready to go. But I'm not. I've been taking evening primrose oil to improve the quality of my cm, but it doesn't seem to be working. Ugh. Any suggestions?