Oof. My mother has borderline personality disorder (BPD), and I have definitely felt similar to this throughout my life.
Have you checked out r/raisedbynarcissists or r/raisedbyborderlines?
Fyi, if you haven’t learned it yet, you will learn soon in your life that attempting to help/fix her is an absolutely pointless endeavor. Point blank, full stop. It only hurts you. Cluster B personality disorders (which your mom shows sooo many signs of) are notoriously terrible at being helped, even by trained therapists. You must keep her at arms length, and focus on healing yourself.
Thanks for having the balls to say this, because yeah, I immediately noticed this.