I was also going to suggest increasing the dose. You might also try a different medication altogether. Each one works a little differently and maybe another one would work better. My two with reflux started on Zantac and ended up on Prilosec. They also would have some small feeds and some where they ate tons. I always thought the small amounts were because they were hurting from the reflux and the big ones were because they either weren't hurting as much or because they were so hungry they just powered through to drain the bottle.

We had a horrible time with DD and her reflux. We switched bottles, sometimes using more than one kind in a single feeding, switched her position, everything we could think of. It was awful. DH and I took turns feeding her because it was so stressful. We had some soy formula from a sample or something and decided to try that. Our pedi said that unless there's a medical need for it, like lactose intolerance or an allergy, they really shouldn't take soy formula because it can be constipating.

Mom to GBG born in July 2009 at 30w6d: 3#10oz, 3#12oz, 3#2oz