Lubrication

From ages 12-15 and partially 16 I had no problem getting wet, my underwear would be soaked everyday. I'm 18 now and I've been having trouble getting wet since I was 16. I wasn't sexually active until I was 18 but I feel like this will affect my sex life. It was never an issue until recently. I'm like the Sahara desert, so fucking dry. I don't know what the problem is, I'm pretty young, I drink a lot of water and eat pretty healthy and exercise on a weekly basis. Nothing is helping. I notice I only get wet a little bit if I watch porn or when I ovulate, but I usually masturbate dry. Any advice or tips from people that have experienced this before? I don't think this is normal, I'm not on any birth control or medication either