Hi there!! I feel your pain :) My son was diagnosed with GERD when he was only 3 months, and he had it from day one. He's been on different medications that worked at first, then wore off....
My trick? My son is a grazer...he eats all day, not just meals. I'm the same way, but I don't have reflux (my metabolism just can't take just the 3 meals a day). So, what I do, is give my son AT THE MOST 3 oz of liquid at a time. Usually, I give this with a graham cracker or something of that sort. You can work up to 5 oz of liquid, but I found that 3 oz was working for us. That's enough for him to feel satisfied, and not enough that he's going to spit it all back up. I do this very frequently thru the day, as it's a "snack." I'm sure if you try this, your child won't be very happy, since it's not much to eat. But, if you wait at least 10 mins to give him more, it should work. It did wonders for us.
Basically, my son gets a lot of meals.....3 main meals (very small) that I actually break up into snacks as well. For instance, I will make him pb+j, and only give him half of the sandwich with 3 oz of milk. 10-20 mins later, I will give him the other half of the sandwich with some applesauce (or milk). Breaking it up helps him to not have too much in his tummy to spit back up, and he's getting the same amount of nutrition, just more often then most. I grew up this way, only because big meals didn't satisfy me. So, it's easy for me to do it with my son. That way, he doesn't see me eating so much, or longer than him.
Just a suggestion....hope you try it!!