I have went to a gastroenterologist and they have found nothing. all my results were normal. but when i go to bed i wake up in the middle of the night because of the stomach acid or whatever it is keeps me up and i have to sit up all night why?

When you lay flat, the muscular churning action of your stomach can more easily force acid up your swallow tube. The stomach entrance is not a valve, but a kink in the tube with a purse string like closure. Intake of caffeine, nicotine, hard chocolates decreases this muscles strength & food/drink before bed increases this process. Avoid them and using acid reducer meds may help.

Your symptoms do sound like acid reflux. You should follow anti-reflux precautions and take whatever medication the G.I. doctor prescribed. If this does not help, further G.I. evaluation maybe necessary. Go od luck.