What are you feeding it on, and how often? And have you repotted it at all over the time you've had it?

Hard to tell if it's potbound, as we have no idea of the size of the plant in relation to the pot. But it should be pretty easy for you to judge - water will run right through the pot and roots will be emerging from the drainage holes. And if you can manage, slip the rootball out of the pot and look at it. If the roots are very dense and circling the rootball and it's difficult to see any potting medium, then yes, it's rootbound and needs a larger pot with fresh soil.

Over watering can also produce yellowing of the foliage - with most houseplants, one should cut back on watering during the winter months, providing only enough to keep the soil from drying out. And don't let the pot sit in water - if there is a saucer underneath, any water that collects there should evaporate or be soaked up in a day, otherwise you should remove it.

PS. writing in all caps is the Internet equivalent of shouting and is considered impolite. And it's hard to read :-)