Maybe a gastric emptying test might reveal something? If your stomach empties faster then it should that might cause you to be really hungry often. There could be another reason. If this continues maybe you should see a doctor.
The growling may be just your body processing the food and not actually hunger. I went through this for awhile, many people asked me if I was hungry! Because they could hear it! So embarrassing! I quit eating when it growled like that. And in a few months.it passed.