It also may help if you make sure your boyfriend has clean hands before he touches you - just think of your vagina as not much different than your mouth - would you stick dirty fingers in your mouth? Same deal!
It is normal for your vagina lips to swell when you are sexually aroused (excited by your boyfriends touch). It is normal for you to 'get wet' (extra vaginal 'discharge') when you are sexually aroused. Sometimes your vaginal discharge will clear and sometimes it will be white as your hormones change during the month. This, too, is normal. If you have painful or itchy lips that make them difficult to touch - and if the 'swelling' is there when you aren't touching yourself or around your boyfriend then that might be worth getting checked up at the doctor but what you're describing seems normal to me.
Make a doctors appointment.. it may be an infection and should be looked at.