Honey my lo is exactly the same. She is a refluxer too. She also went through a nursing strike at three mo. I was so paranoid that I would collect all her nappies to make sure she wasn't dehydrated. Now she is mo and she is taking about 24oz a day also. So don't worry, they will not starve themselves. You just gotta make sure she is having enough wet nappies in a day? My lo on a typical day would only eat 90ml 1st feed, then 140ml, 120ml, 90ml, 120ml, and sometimes another 70ml in the night.
Also some babies are born with smaller stomach compactly, so they can't last as long between feeds. I guess 4hr easy at 4mo is only a guideline. Some babies need to be fed more frequent and bigger babies less frequent.