"Where, oh where, do I go to find shoes in a large size?" you ask. Here are some suggestions. I found a site that has a "where to go" chart by on-line store and gives sizes that can be found there. It is http://www.alaska.net/~kathryn/heels.htm There are no doubt others, but I found Kathryn's site a good one over all. 'Kathryn' also has other clothing categories on her website which provides a one-stop shopping experience.
I remember when J showed me pink tennis shoes in size 12, proudly holding them on hands outstretched, grinning from ear to ear. "Do you know how hard these were to find in my size?" she said. It seemed that on-line was her only option. However, J found the pink tennis shoes at PayLess!! Checkout online stores such as Zappos and Barefoot Tess --- Heels, tennies, and more --- . I hope this helps! Good luck!