I'm glad that made you feel better. It's a hard thing to admit! My best friend IRL happens to have the same issues w/showering that I do and it took YEARS for me to figure out that it was because of the fear of what I might miss while I'm in there, what I might not hear. It was kind of a breakthrough for both of us when I figured that out and shared it with her. So, no, you are not alone.

I haven't even really talked to my T about that issue because it's so personal and icky, lots easier to post about it here where there's a degree of anonymity.