You struggle to find words - you remember being a grownup, but most of your knowledge is out of reach. "Pwease..." You have to fight to make the words come out. "Pwease. Don' wanna be girl! Don' wanna be baby." tears roll down your cheeks, and you feel the infant part of your mind about to take over in a real screaming wail.
Could be that Red guesses that as well. "I forgot about babies screaming and pooping. Maybe I don't want a baby sister after all. Do you promise to be a good boy? If I change you and make you male again, will you do what I tell you?"
You nods. "Yeth! Oh, pwease make me a boy again!"
Red grins at you. "OK, since you said 'pwease.'" She picks you up and carries you back outside, putting you on the ground. As soon as she lets go, your diaper disappears. You hope she gives you clothes when she changes you back, but you'll streak all the way home if you have to to get away!
You feel the changes start, warmth and pulling. You are getting bigger! A glance down confirms that you are getting male parts again as you mature quickly, 3 years old, 4 years old, 6 years old. But something is wrong. Tawny golden fur is appearing on your legs and belly, and your male parts are starting to get covered by a sheath. The size of an 8 year-old now, but your arms are changing shape, and your hands are bunching up into.. paws?
You yell as you feel your head changing, skull shrinking and your face pushing out, but what you hear is a loud, deep dog's bark! A final spasm of change gets you up on all four legs. When it is over, you twist around and stare at yourself. You are a boy - a boy Great Dane!
Red giggles. "Now you are a very good boy." She pats your head, and you feel confused. It's hard to think, but Red seems happy. That makes you happy, for some reason,a dn you wag your tail. No! You aren't a dog! Or are you?