A lot of the info you gave here are more "history of the universe" than actual motivations.
As said by False God, once you strip the background informations, the motivation is pretty simple:

Revenge for (1) deaths of her kind and (2) betrayal of the gods.

Some ways I see to deepen the motivation:
+ Is there a specific god that she consider betrayed her more than the others? That would make the revenge quest more personal than just "kill all the gods".
+ Is there a god that joined her side but was eliminated/intimidated into submission? Or at least a god that was more willing to hear her claims?
+ Is she still magically bound by some of the oath she made when ascending, adding to her objectives a will to free herself?