Sex during pregnancy :(

I am 27w 6d. I was a nympho before I got pregnant but the last 2 months I feel like my vagina is swollen and it is so uncomfortable. He will go down on me to get me wet and it feels like my stomach is jumping does anyone else experience this? What is the best position that is comfortable let me just add I'm pretty small and his junk is big so I he can't go all the way anymore I just can't take it. What lube is safe?