The stresses and strains of everyday life can cause you to eat more, eat things to make you gain weight, and also eat between meals. If you don’t believe this or think you are immune from doing such a thing, why don’t you check it out.
You can make a stress/food diary in which you would write down each stressful occurrence and maybe even rate on a 10-point subjective rating scale the severity of each stress. You would also write down how many between meal snacks you had on that day and how much you ate at meal times, and what foods you ate for snacks and meals.
Keep the diary for 7 days, and see if there is a difference in your eating pattern on stressful versus non-stressful days.