I haven't found a way to relieve the pressure of a baby in the ribs, so I can't help you there! Nipples leaking right now is very normal, and you can get pads if it gets too bad. You are having contractions after you have sex, it's normal to get contractions after you have an orgasm, as long as they aren't extremely painful, or lasting a long while after, it's fine! I get them every time too. Actually, having sex 1-2 times a week while pregnant decreases your chance of preterm labor.
I get the same uncomfortable feeling sometimes trying to sit but if I lean back for relief, I can't reach my food anymore lol. The baby just needs to readjust. And the clear stuff is normal. You can buy nipple pads if it comes out a lot. You should definitely talk with your doctor about the cramps, but in the mean time are there alternative positions you and your partner have tried that don't cause the pain?