Acidity is directly dependent on the type of food eaten how much eaten and when. If your timings are varying then acidity is common. Also it depends on your mental status. Stressful nature causes acidity.
Next Steps
To start with have food at specific timings breakfast lunch mid evening snacks and dinner at specific timings ealry and heavy breakfast and early and light dinner will help
Health Tips
Avoid oily fried foods and also stop milk as milk causes bloating and gas, instead have curds and buttermilk