Ok, here's some of what I found
**just my experience/just my opinion**

Celexa is almost always prescribed as an evening/hs dose.
The Wellbutrin XL is usually morning because of its' possible stimulate affect.

With both drugs, you are still in the early stages...this may be causing mood swings, agitation, irritability.
It might be a good idea to check in with your physician.

And Wellbutrin is to be used with caution with any eating disorder as well as any oral diabetic agents.

You may not be getting enough nourishment from what you are eating--I understand since I did the same thing when I lost my weight.
If you can spread out the times when you are eating and what you are eating, there is a better chance of regulating your glucose level...
Do you have access to the food guidelines? Many people don't realize that our bodies do not need as much food as we put on our plates--but we do need the right balance of protein, carbs, and fat.
I'm sure you know that your glucose level can affect your mood.

Tao, in no way is this to take the place of your physician's treatment protocol. I am no longer an active professional...

These are small changes you can make that can help your mood. Please check in with your physician. At minimum, she/he needs to know what's happening.

Honestly? I think there's something going on between the meds and little food...jmo.
When I was losing excess baggage, my meds had to be adjusted based on my lower weight. 20 pounds is good, but if you are losing it too quickly it will make you weak.

Lots to think about...
Cap