Having looking in all the rooms, and not feeling like going out for the moment, either, you decide to return to your room and wait there. You walk through the corridor, that strange feeling returning to you again, every time you pass in front of the windows, unease in the dress. You try adjusting it again when a shiver runs through you, but you discard it as you open your room door and walk inside. You pass in front of a full-length mirror avoiding to look at you wearing the dress, but you catch a glimpse of yourself that makes you stop dead.
At first, the dress just hung loosely around you but now it seems to suit you fine. Oddly, you can see the fabric cling tightly around your waist, making it look smaller. Even the neckline, although still loose, have a bit of... cleavage?! "It...It can't be!"
You think, stepping closer to the mirror. "It is! breasts! but not even a fun house mirror could do that!" Then you look down and gasp. "I have breasts!" Your hands come to your new chest to verify, and are met with two soft mounds. They're real. This is real. Isn't it? It's far to vivid to be a dream. But it's everything you've ever dreamed of! Tears fill your eyes and you almost laugh, but you stop in worry that somehow this isn't real and will end. How did this happen? Then you realize, the light! Whenever you passed through the light while wearing the dress you changed.
You run as fast as you can back to the nearest window, needing to experience more of womanhood before you wake up or something. As soon as you arrive the sun comes out from behind a cloud and it pours in more brightly as if beckoning you. With trepidation you step into the light, and to your again tearful delight you feel your body changing again. You hug yourself and giggle as you feel your curves filling out. Then you fall to the ground and spread your arms and legs, basking in the warmth that makes you more female every second. You feel the warm going deep inside your body and you swear you can feel it changing your very DNA, altering those Y chromosomes into X'es. Your waist shrinks, your hips widen, your butt plumps up and your chest soon looks perhaps bigger than that of any girl in your highschool. Your face tingles for a bit, and you know you just got prettier, but you wonder if you are very pretty or not. Even if you're not you'd be happy though just to be a girl. Then your groin feels warm, and in bliss you await your final change. As your genitals shrink and pull inside of you you sigh in utter delight. Now you feel complete.