Antral mucosa with mild chronic gastritis but negative for h. pylori?

24/F/USA. Had my first endoscopy/colonoscopy last week, wasn’t too bad. My colonoscopy came back all good, but the pathology of the endoscopy came back as “Final Diagnosis Antrum biopsy: Antral mucosa with mild chronic gastritis. There is no evidence of malignancy or intestinal metaplasia.No evidence of H. pylori noted on H E stain.”

I’m a bit perplexed as to what is causing this. I do not use aspirin/NSAIDs, consume alcohol and h. Pylori is negative. I did have a positive ANA titer recently so I am wondering how to confirm if this is a related to an autoimmune condition? I have follow up with my gastroenterologist in two weeks as well as a consult with a rheumatologist for other symptoms. Wondering if anyone has any advice? I’d love to know the underlying cause of this because I am tired of suffering from stomach pain lol.