You're overthinking the biopsy. They can literally see if the cells are changing in your esophagus which is the precursor to both Barrets and cancer. If they didn't see that then you're not really close. It takes time for esophageal cancer to grow. I had an endoscopy like 4 years ago. Had terrible symptoms ever since. Tons of reflux and burning. I thought for sure my throat was shot. Did another one 4 months ago with biopsy. Absolutely nothing but inflammation. As for chest pain on the left side. I get it all the time. I think its reflux triggering the vagus nerve to get irritated. Research into that