She could be draining you unconsciously, at times vampirism is a trauma response too and not intentional. Try banishing her energies from you and your space any time she comes near you, also try cord cutting and definitely perform shielding and see.
In a sense, I consider it anything you do which “shields you” from negative influences, energies or a specific thing - not sure if the definition other people have here is different.
A personal example, I carry a consecrated obsidian pendant with me for protection and a few other reasons, but I’ve also created something similar to it astrally so that I get the same effects even if it’s not with me that day/time.