Thanks for a thorough question and a details about tests.
Since you have mentioned about your past history of depression you are likely suffering from stress induced non-specific chronic gastritis. After ruling out all other causes that may cause chronic gastritis, this looks like the only cause. However, please do not take this as a final diagnosis.
I would recommended to visit a Psychiatrist who can council you and guide you properly.
Meanwhile, you can reduce your stress by changing your lifestyle e.g. get into hobbies, sports, gym, exercise, avoid smoking if you are a smoker etc. After changing your lifestyle, you can visit your Gastroenterologist and he will prescribe you medicines to control your gastritis.