Bio Gender by Aaron Pery
Approx. 15,800 words.
Published on September 18, 2011.
Dr. Paul Rice is a physician and brilliant biochemist who spends most of his life in experiments that would release his female alter ego.
Then, once he's certain that he had found the right formula, he injects himself with the serum.
Unlike with Dr. Jekyll's, his creation isn't a monster but a beautiful young woman who, pleasing him greatly, replaces his physical and mental being.