I know how youre feeling! I never had myself down as an 'emotional eater' and I had been sticking well to my diet, but then coursework, deadlines, tests and exams all started to appear at the end of term and suddenly its so much harder to resist that plate of chips!
Also ive found that when im more stressed it tends to be because im working harder and for longer to get things done and the last thing you want to do after working for 10 or 12 hours is come home and prepare a meal, so when someone suggests take away... need I go on?
For me its less of the, "Ok, ive just had such and such happen so I need a donut to calm me down" maybe thats whats going on the back of my mind I dont know, but it doesnt seem that simple some how.
All I can suggest is to keep a range of healthy things to reach for around, it probly wont help you kick the habit of reaching for food when youre stressed but it might help limit the damage. I use diet pepsi, not exactly healthy I know but it can help keep me off the choccies.
Like Mal said, try to take youre mind off it and do something else to releive your stress.
If the stress is making you feel bad, and youre basically using food to cheer yourself up, try doing something else that will have the same effect. Like going shopping, having a bath, watching your favorite film, whatever else makes you happy apart from food.
Hope that helps!