I get acid reflux after eating a lot, i've taken antiacids which didn't work, proton pump inhibitors which didn't work well, h-pylori was negative. ive cut out all foods that have a risk and done everything adviced like raising the bed.

Reflux: It sounds based on your post that the reflux symptoms happen after you eat a lot. The main change will be reducing the quantity of food eaten at one meal. Stay in touch with your pediatrician and gastroenterologist. Usually work up is needed in order to assign symptoms appropriately. Losing weight if overweight will be critical in the long run.