Well, my T tends to call me on it if he thinks I may be projecting (whether on him or someone else). It has helped me become better at realizing when I'm doing it with people.

If you have the feeling, maybe bring it up with her? Check in, see if she felt frustrated. If not, likely projecting. Though even if she did feel a bit frustrated, there could still be projection involved (if she's good at hiding it, say).