I also have experienced pronounced shrinkage of my flaccid penis post prostatectomy and radiation for prostate cancer. I understand that there is some shrinkage with age and development of a pubic fat pad. I've lost the excess weight but that fat pad has not gone away. My gym has communal showers and I use them with some embarrassment. As one of the commenters mentioned above, although circumcised at birth I now look uncircumcised. I tried the vacuum pumps but had difficulty working them and they caused bruising and I discontinued them.