Pain during sex!

Tayste
Okay so when my fiancé and I would have sex in the past, it would hurt a little but since I've been pregnant, it's hurt so bad! Like I can feel him hitting the end, like in the lowest part of my stomach. We can maybe go for like 10-15 minutes before I am nearly in tears from the pain! Is it just where everything is swollen? It hasn't been the whole pregnancy, just recently. I'm 21 weeks. I'm to the point where I want to cry because I want to get him off (since I can't go long enough) but every time I think of giving him a bj to get him off, I feel like there's something wrong with me. 😭 tips on what might be wrong? We've changed up positions but so far, nothing has helped.