The loud noise and gargling feeling in the stomach is probably due to increased gas production in the large intestine.
I assume over the period of time you yourself might have formulated a comfortable diet plan for you. So I can understand why you feel that food items are not the reason from this. But there is high chance that certain dietary patterns can cause this.
I recommend the following steps. Please note, you need not follow all these recommendations at once. Give it a trial and error method and see which works. The following are the most common reasons for your symptoms.
1. Several foods contain the carbohydrate raffinose, which is poorly digested and can increases gas production. Foods that contain raffinose include beans, cabbage, cauliflower, Brussels sprouts, broccoli, and asparagus. Avoiding these foods or eating them infrequently may reduce the amount of gas you produce. Starch and soluble fiber can also contribute increase gas. Potatoes, corn, noodles, and wheat produce gas while rice does not. Soluble fiber (found in oat bran, peas and other legumes, beans, and most fruit) also causes gas.
I understand this is a big list. You need not avoid all of these at once. But go for a trail and error. If any of this forms a major part of your diet you should try eliminating them for a week and see whether this brings any benefit.
2. Lactose intolerance. Since you are comfortable with milk and milk products this is less likely. However you should have a milk and milk products free week and see whether this improves the symptom.
3. Bacterial overgrowth in large intestine – This could be one reason for the loud noises and related symptoms after food intake. A course of antibiotic is indicated in this case. I usually prescribe a quinolone antibiotic like Norfloxacin or Rifaximin. You should discuss this with your Doctor and get a prescription for a course of antibiotic if indicated. Once you finish the antibiotic course a course of probiotics can be taken.
4. There are some medications like Beano , Simethicone, activated charcoal, Dicyclomine etc that can help in this symptoms. But I do not recommend them now. These are indicated only if the above measures fail and if the symptoms are really troublesome.
Since do not have any other major symptoms of IBS (constipation / diarrhoea / cramps) now. That means your disease is not very active. Try the above measure, the noise should reduce. Anyhow the particular sympotom is not dangerous nor it is a warning. It is just part of the IBS spectrum.
Hope this helps
Please feel free to ask followup questions.