Not having any sort of passive healing hurts Bellelba a lot and she has to rely too much on potion MPR.
The more you crit, the earlier you get defence crush 2 procs, good flinch timings and less you get flinches or nat crit the less potion you require. Ideally you need 4-5 potions on bar 1, 2 on bar 2, and 2 on bar 3.
Use both crit shields on bar 3 because you lack bulk to tank the 2nd wood hammer. And you have to finish it before the brutal swing comes through.
EX should make it much more bearable.