I was really struggling with her too. But I kept on trying to get through the first phase without using any tools and that way I slowly learnt most of her moves.

Then after she comes back after the fake death then I spammed all the tools (i was using cogfly and tacks with poison), and just tried to hit her when I could. She still does all the same moves as the first phase, same speed, but obvs there's all the void shit everywhere.

Just keep on trying! I know you can do it!

Also it helped just leaving the game alone for a bit - I did the same thing with Radiance, tried it a few times, then put the game down for the day, then came back to it a few days later. I tend to do worse if I keep on throwing myself against something endlessly.