Bacterial Vaginosis is usually an infection, which is why in most women that suffer it, it smells. It smells like tinned sardines . Pregnancy does cause increased CM, and it can be quite watery, but not enough to completely soak your underwear and pants. Over the course of a day you may find that your undies feel wet, but not soaking.

There is a thread somewhere with how to tell if your waters have broken. From memory you go to the toilet and fully empty your bladder, then you either cough or stand and sway your hips, if you feel a fair bit of wetness than it could be your waters. Amniotic fluid is meant to smell like semen, but personally I can't smell semen so I dont know what it smells like.