My stomach is always making rumbling noises, whether or not I have just eaten. I never have much gas though. Noises are very loud. What is this?

Peristalsis . Your stomach, small bowel, and colon contract throughout the day regardless of food intake. This is a normal process and sometimes loud enough to be heard.
Borborygmi. Stomach noises are called borborygmi. If you say it in a deep slow voice, you can understand why it was named that way. As fluid and gas moves through your stomach, it causes those noises. A more active bowel often will be noisier but it's not always associated with more gas.