Have you been checked out by a GI Dr. to see if you have an acid stomach or something on those lines...like Gerd or Acid Reflux? You said you have kept a log of your eating have you noticed anything that seems to bring it on more?
Seeing your a college student is it possible your a bit nervous over things and just need to wind down at night? Many years ago I had something similar and my Dr. said I had a nervous stomach, as between trying to raise 2 young children, take care of a house etc. etc. I wasn't eating properly and by the time nightime came my body was just too wound up.
You said you have been a bit depressed, but is it over not feeling so hot or is there something actually bothering you? If your regular Dr. can't seem to get to the bottom of it, I would see a GI Dr. to make sure you don't have something going on.
Best wishes and hope you feel better soon...JJ...