The loud noises your stomach are making are called borborygmi, which is just a technical medical word for 'loud stomach noises.' If you do not have any pain or other serious symptoms, then you do not need to worry
about this, as it is perfectly normal.
The noise comes from the contractile activity of the stomach and intestines, called peristalsis, pushing through stomach contents, digestive juices, and gases. The rushing or gurgling sound comes specifically from the movement of the gas bubbles. Having these gas bubbles is normal and doesn't necessarily come from eating 'gassy foods.' Rather, all of us swallow a lot of air when we are talking and the like, and this is the gas that gets pushed through the intestines.
The intestines and stomach have an internal timer that causes them to contract in a coordinated fashion several times a day. This is a housekeeping function which keeps the intestines tuned up and keeps digestive juices moving the right direction. Importantly, this will happen regardless of whether you eat or not, so it is not necessarily related to your meals.
Talk to your primary care doctor
if you have any other concerns or questions about this issue!