Is my pregnancy causing me to be dry down there?

Ok i know... TMI but i really need your help. I am 20 weeks pregnant. I concieved my baby the day before my husband was deployed to afghanistan. I never had a problem staying lubricated down there. Actually the sheets always ended up pretty wet. Now my husband is on his r&r leave and we had yesterday bt i was dry within minutes. I have noticed that since i was about 5 weeks, i have been pretty dry down there. It really made the painful so i had to stop him. Is my pregnancy causing me to be dry? My doc always says im fine during every appointment. is there anything i can do naturally to become more wet down there? Also will this continue after my baby is born? Any answers will help. Its not just that is painful. Its always kind of sore from being dry. I do not have an std and i have also been checked for uti's and yeast infections and i dont have either. i have tried using a lubricant so it doesnt bother me while i am out and about but i found that to be very messy.