I have the same problem. I will go to the loo empty my bladder (well so I thought) and then sit back down only to feel a tiny bit of wetness come from the top of my V (I mean the top where the lips start). It smells like urine and it gets really annoying. I have only noticed in since being my third trimester. I mentioned to Dr and he said its due to hormones. I am going to have to wear panty liners from now on cause I feel paranoid.
On the pelvic floor exercises. I just bought a neat product called epi-no. Its a device that helps you exercise your perenial for child birth but it can also be used to train your pelvic floor. I just got it and haven't started using it yet. But am keen to improve my pelvic floor thats for sure. Google it and see what you find.