C.L.
It could be a growth spurt? Is she learning a new development skill such as sitting up- that always messed up my daughter for a couple weeks. I think you should continue giving her as much food in the day, but I wouldn't feed her at night unless you are sure she is actually hungry. 6 months old can usually go all night (10-12 hours) without eating, but they still will wake up for cuddling or nursing if you let them. Sleep was super important to me, so I put my daughter on a strict feeding schedule and she was always in the 99% so I didn't have to worry about that.