I can gain three pounds by the end of the day (morning weight vs. evening weight) without having TOM. The next morning I am back down. I wouldn't worry about 3 pounds.

Check the ingredients on the Midol for caffeine. It is advised that PMS sufferers avoid caffeine.

I prefer aspirin if I am having pain during my TOM. Some women say it causes a heavier flow, but I don't see how.