Stressed out and eatting like a trash compactor...
At least not stressed out and eating FROM a trash compactor...
Seriously, some good suggestions above. Very often the urge to snack has less to do with filling your stomach than with chewing, which is where the nervous response to the stress comes in. So fillers like oatmeal, while healthy, may not satisfy the oral urge (don't go there).
I'm a terrible snack eater, munching all the time, and my personal choice is veggies, which are generally non-fattening, healthy, and can be filling, too. If you buy a prepared tray, just use some some discipline and toss out the dip if it comes with one, or give it to a friend. And don't ever put mayo or other dressings on them.
Better yet, of course, save the added cost of a prepared tray and buy fresh veggies whole, like carrots and celery, and cauliflower and broccoli if you like those. You can also buy bags of little bite-size carrots that don't need peeling, and you don't have to sit there gnawing on a whole carrot like Bugs Bunny, just pop them into your money like candy.
Certain nuts are good snacks, too, like walnuts. Which happen to be a very high source of omega-3 fatty acids, kind of a surprise to people who think it only occurs in fish.
But bottom line, I think while you remain stressed you're gonna wanna chew, no matter how full your stomach feels. So don't fight it, just chew the good stuff.