ower.

Thanks in advance for your help!
Paula

Your problem seems to be that you have no way of getting air to the
bathroom for the fan to move air out of the space. You could test my
theory by leaving the door open. (Geez, take a shower with your
clothes on if you have to for the test.)
The solution is to put a louvered vent above the door or even in the
bottom of the door if possible. That's the idea.