if i were you, i would not bother with the df. for us, it seemed to cause more night wakings than anything. and it was sort of nerve-wracking to drop.
does she take a full feed at her night wakings? it seems that at her age, she should only need one feeding in the night, if any. if she is just waking and not taking a full feeding, it is out of habit and a df would not help in this area anyway. also, the fact that she is not hungry at 7 tells me she doesn't need the 2 feedings in the night and maybe none at all.