I sometimes have to take a quick pee break. Its inconvenient, but it helps.
I felt like that both times I was pregnant. Between the baby pressing on your bladder and having intercourse, it'll sometimes feel that way. Maybe try to empty your bladder before hand just to see if that helps it. You may just need to find a position that doesn't cause that feeling.
I'm 22+3 and have the same kind of problem. First and foremost being worried about squishing the baby. Not to mention that I run out of steam so fast that even after 10 minutes of exertion I'm already wiped out and pretty much leave the rest up to him!