make sure to have protection on when dealing with spirits.
you can invoke her. tell her to come out, and show herself, "or else". if she is your guardian, she is a shy one. most demon guardians i have known (like 3 - all my friends get them, but not me wtf?) are very straight forward. be benevolent yet cautious and comfortable around her. if she is sinister, or not a guardian. get rid of her. demons need to know that mortal souls wield power greater than them.