I agree with mrsreeder2be about the pad to check for leakage! As far as your mucus plug....it is different with every woman! The mucus plug come loose when you dilate! You can loose it slowly over a few weeks (which makes it look like you have an increase of discharge) you can lose it before labor when your water breaks, or right before you give birth!
The other thing you can do is put on dry undies lay on your side for an hour because when your water breaks the baby's head falls down and in a way plugs the hole where the water broke thru. So if you lay on your side for an hour that gives the baby time to sorta swim back up a little away from the hole and allows more of the fluids to go under the head so when you get up in that 1 hour time and you have another gush of water then its probably your water breaking. And like previous poster said only a small % of women's water actually breaks on its own. I had heard 10%. My moms water broke with her first pregnancy with my sister but the dr had to break her water with my other sister and me.
A lot of times moms get it mixed up with leftover urine since our bladders are so squished right now we may think that we emptied our bladder but once we get up and baby readjusts they sometimes will push a few drops out and it will feel like a lot.
Best way to determine if you're leaking fluid is to put on a pad. If you soak through it in an hour or less,then most likely its your fluid! Only 15% of ftm actually experience their waters breaking though!
You might not know if you do loose your plug or not. I have no idea when I lost my plug with my first. Pretty sure I lost it after my water broke, and I was in labor already. LOL.