Unexpected diagnosis from urologist gyno

I have seen my urologist today after a long wait the reason for my visit was Botox for Vaginismus, after examining with just by looking with her eyes she came to the conclusion that I had something called “ vaginal atrophy” and prescribed me estrogen cream to use down there, mind you I have never been on birth control never had any chemo or hormonal pills my estrogen levels are fine, does anyone know what this condition is ? And why would my urologist assume I have it ? Everything I have googled so far about the reasoning why someone would have this does not apply to me.