For the 10 years prior to the correct celiac disease Diagnosis my husband's depression was deep enough to need medications but he could not tolerate the side effects. He had depression to the point of thinking of not living anymore. I'd go to work and worry about him all day.
After going gluten-free his depression is not as severe, but yes it does exist at different levels depending on the day, week, etc.
His body took a beating by being misdiagnosed for 26+ years and he's dealing with other health issues that are offshoots of celiac disease and that at times has him depressed.

Mandigirl: Don't worry about losing your jean size, concern yourself with staying healthy.
It appears that you did, in fact, develop an eating disorder as a result of realizing that you can only eat gluten-free.
I remember doing what you are doing when I was in my teens and early twenties (trying to expend calories for each calorie I ate) - and guess what -- I got over it! (I have had overweight issues since I was 12).
I learned that while calories matter, sometimes it's the carbs that keep weight on and when I want to lose weight I decrease carbs (sugar, corn syrup, breads, too much fruits or juices, wine, etc. ) and watch fatty stuff (fried foods, too much mayo or butter) and I will lose weight.
However, I think your gluten-free diet has made you more aware of the foods you CAN have and you have snowballed it into a mania.
Please tell the doctor who is giving you Welbutrin about your eating issues. Welbutrin's side effect is to diminish appetite (I was on it once so I can talk about it first hand). Let the doctor decide if Welbutrin is contributing to your dining issues.
I'd like to add to Pauliina's observation: were you tested for Vitamin levels, such as B12? Sometimes deficiences cause cravings - perhaps a monthly shot of Vit B 12 could help?