". I have a problem with completing my work on time and spending enough time studying."
Everyone has ADD to that extent. If you find something boring, you're going to have a problem doing it. It's like when they put little kids on meds for ADD because they're bored in school and acting up.
Food is also related to concentration problems. Dairy, Sugar, Carbs like bagels, bread, cereal..etc.
Try writing down what you eat and see if you see any connection where the "ADD" symptoms are worse.