I would say you need to document all the incidents. I don't know the level of confrontation you are comfortable with, but consider actually recording all your interactions with her when you are alone, voice or video. Notify her when you do this of course. Make explicit requests to not be touched. Like this, no matter what happens, you have evidence of what has been happening.

Consider this, if she is inappropriately touching you and has now started stalking you outside the workplace it might (soon) be sufficient for a restraining order which doesn't depend on your faculty's interpretation of things. It might sound over the top now, but maybe not so anymore at one point in the future.

Document everything, at the very least that would make it hard for her to slander you when she feels too rejected.