OP, are you overweight?
I have suffered with chronic GERD for over a decade. It's not until I got my weight down to a healthy level that the symptoms subsided, naturally my improved physique is the result of a better diet with less processed foods.
Greasy, spicy and garlic laced foods as well as alcohol used to trigger me, but now it's very rare I get a flare up when eating these foods, and I 100% put it down to being slightly overweight (90kg at 5'11 and male).
Down to 75kg now and feeling better than ever. I can count on one hand how many times a month I need to take medication now.
I do still sleep with my bed propped up somewhat and on my left hand side as another poster suggested.
I abused lansoprazole and omeprazole (cheaper of the two) for nigh on 15 years on prescription (60mg a day), so much so that I became anaemic and defficient in b12, the reduced pH of your stomach makes it harder for your body to absorb vitamins and other nutrients, though I expect your doctor neglected to tell you this just like mine did.
Please try and make lifestyle changes instead of relying on drugs if you are able to, stress is also a big trigger of GERD.
Chronic GERD can lead to stomach and oesophageal cancer, so please take treating the cause seriously.
Some other underlying causes can be hiatus hernia (can be diagnosed by endoscopy), H.pylori infection (ask your doctor to refer you for a test).
Ask your doctor for acidex as it provides instant relief, omeprazole takes 6+ hours to work.