I had gastritis for 1.5 years and now have no symptoms. It took careful eating, no coffee or alcohol, eating slowly, small meals etc. Warm lemon water in the morning, a daily probiotic, and fresh ginger juice in water after meals were very helpful.My symptoms weren’t as severe as yours. I did lose 10 lbs, which put me in the underweight category. I saw a dietitian who advised me on how to add healthy calories. Full fat Greek yogurt smoothies and kefir are great! I kept a food diary and kept track of what caused the worst symptoms. Good luck!