Hello! Honestly, I don't have any answers, I'd just like to jump in here as I think our DD are twins! We have a very similar schedule, minus the fact we aren't on solids yet. S also has reflux and is on Zantec. S is 5.5 months (sorry, lost count of weeks), but will be 6 months March 6th. S is BF, are you doing formula or EBM?
Have you tried not feeding at 4:30? I can usually get her to only nurse at one of the NW, though not always.