Gastritis Support Group
Gastritis is a medical term for inflammation of the lining of the stomach. It means that white blood cells move into the wall of the stomach as a response to some type of injury. Gastritis has many underlying causes, from infection with the bacterium H. pylori, bile reflux, or excessive consumption of alcohol or certain foods or drugs like aspirin.

For me, high fiber foods and raw veggies gave me problems. That said, taking metamucil once a day really helped my overall symptoms.
You would think that caffeine and alcohol would have made it worse, but I never really noticed it having much of an effect either way. (Though I'd say to avoid those in general with your tummy issues and I know you already do.)
I'd also be careful with oats and wheat. I know you're keeping a journal, so perhaps you can get some clues. It took me a long time, but I think I've finally identified oats as a problem food for me, and I ate a lot of oat products.
Also, foods super-high in fats can be a problem... though I've done fine with most nuts. I don't eat meat, but I do remember beef and other meats giving me a lot of problems when I did. (Chicken and fish not so many problems.)
Good luck and keep us posted.
I don't drink alcohol or caffeine any more as you know with the G. I'm sure the coffee would help me on the C days.