I really like your additions to the story! Your writing reads really well and makes me emphatise with Jon. And while inanimate transformation is not my first choice of theme, the story of Jon as Sarah's breasts really does play well to the kick I get from feelings of powerlessness from being totally in someone else's control, as an uncomfortable sexual object...
Take a look at some of my episodes. There isn't very many of them but if what I like also resonates with you, you might enjoy them!