Vaginal swelling during/after sex

I am sexually active with a man who I have been with for 2 years. When we have sex the sides of my vagina become noticeably swollen. Sex is uncomfortable and not enjoyable. There is NOT severe pain, only swelling that goes away after about 10-15 mins once we stop.

This happens every time. We have tried all types and materials of condoms as well as no condoms (I am on birth control). It swells even when we are going very slow--roughness is not what causes the swelling. We have also used different forms of lube as well, all of which has not helped.

What is wrong?! If anyone has some insight, it would be greatly appreciated. I want to be able to make love with the man that I love.