There is a new(ish) article over on Precision Nutrition about the food/mood connection. Basically, how emotions and feelings and mood are affected by, and influence, what we eat.
Food and Mood
It's a good read and if you're struggling to get a handle on what you consume, it's not a bad place to start. It's got the inevitable plugs for their programs and coaching and training, so be aware they'll show up. But it doesn't detract from the value of the information.
Best take away bit? You need to change how you eat one habit at a time. Master one every two weeks or so until it's yours and then work on changing something else. Don't try to do everything at once.