Look closely at what you eat, as many foods create mucus. Dairy is a big culprit for some people (I am one). Google it. You will find suggestions for foods to avoid. Water thins it, pineapple juice thins it. I fight it too.

I'd suggest you talk with your doc about a couple of possibilities: more water, even twice what you're drinking now might not be enough to make a difference; greater doses of mucinex; nebulizing saline solution and albuterol; practicing and using the Huff method of coughing; percussion either manually or using a vest and postural drainage. There may be other things to try as well.

I fine that if you drink something hot it helps get rid of the mucus. Also if you gargle warm salt water. The Nebulizer helps loosen the mucus