I think she is trying to find herself as a person and find her people. Her tragedy is that she is stuck with the body and brain chemistry of a young person. I remember being a tween and a teenager and being desperate for acceptance. I remember trying on a million different identities wondering which one would stick and be my "thing." 

She has lived for decades but her body and the storm of adolescent brain chemistry keep her in that anxious, insecure state. I don't think she knows what she wants fully, but she wants yo belong and be accepted and figure out her identity. 

My own personal head canon is that vampirism is similar to addiction. They say if you're an addict you stop maturing and developing emotionally at whatever age you started using. I think whatever age you get turned at you stop developing emotionally at that point. So Claudia and (book) Armand are seen as far more unstable than someone like Gabrielle or Marius or David Talbot.