I would definitely try seeing a nutritionist, as others have suggested.
I'm so sorry to hear about this - it sounds terrible! I can relate, as when I'm on a diet (as I usually am) I can get obsessed about food, but it's more about the number of calories I have left and how to spend them. All the same, it's distracting and distressing and I sympathize.
But you might also look at <i>what</i> you're eating, and you might look at eating l
ow-glycemic foods. Kicking off the day with cereal alone is a recipe for disaster - it's revs up your metabolism and sets you up for a crash as soon as the simple sugars are gone.
Have you tried starting off with eggs and bacon and orange juice instead? Or yogurt and granola? Getting some slow-burning protein into your diet early on might help.
The fact that your twin brother has similar issues points to a genetic metabolic issue. If it's psychological rather than physiological (although odds are it's both) you might look at your relationship to food as children - was it scarce? Was it used as a reward?