10 months old and still not sleeping through the night

Hi. My name is Bridget and I have a 10 month old baby who has been diagnosed with GERD and being treated with 15mg of prevacid daily. Since starting the medication at about 7 months old my son has done well-he has doubled the volume of milk he gets and sleeps better . . . However doubling the volume means he has gone from only 6-8 ounces during the day to 12-14 ounces. He used to feed every 1-2 hours at night, now its every 3, which is better but still pretty exhausting. My pediatrician says I need to contiue feeding him at night because he is still not getting enough fluid during the day. My question is if I continue to do this will he be 15 months and I will still be getting up at night? We also rock him to sleep and I have thought of strating some type of sleep training to get him to fall asleep on his own-I just think that if I continue to feed him at night, forcing the issue of sleep training at nap and bedtime will give intermittent reinforcement and just confuse him. I've also heard the cry it out method can provoke symptoms. I guess I'm looking for any advice, suggestions or clues to help. I am nursing, but I supplement with formula as well. I know poor sleep habits are part of GERD, but if the GERD is being controlled what should I do???