You are a young dragoness, but a few second ago you still were a rather dashing prince.
Usually evil dragons kidnap a princess or a prince before turning them into fellow dragons, by raping them. But your kingdom somehow resisted to the assault of an evil dragon installed on its borders for generations until today, when he came to your capital and successfully killed all the royal guards, turning the whole city defenseless. So secure was he in his victory, that he raped you then and there, under the gaze of your parents, the queen and king.
That you were male as a human is irrelevant. The evil dragon that raped you was male, so turned into a female dragon, which is called a dragoness. Just like any person raped by an evil dragoness would turn into a male dragon, regardless of what gender they had before.
Thankfully, as your transformation finished, you attacked your rapist on reflex, killing him in the process. Sure, it won't rebuild the city, resurrect the guards or turn you back into the dashing prince you used to be, but at least the kingdom won't suffer at the claws of this dragon.
… And you're more than willing to protect your country.
"Father, Mother, I know can't claim the throne anymore, not being male anymore, or even human. But you can count on me to help defend the kingdom against other dragons and protect my brother."
But the king, your father, refused. You didn't know, but he have a profound hate of dragons since his brother was kidnapped by one. "How could I trust YOU to protect my kingdom or my heir? You're not human anymore. Heck, you're not even a mammal!
He was right. You may have turned into the only known reptilian species to be hotblooded, you were still a reptile. With a gigantic, scales covered quadrupedal boobless body. You also gained a long, prehensible tale, five clawed paws, each paw having one of its claw acting as an opposable thumb. You could feel your new body was made to walk indifferently on two or four legs, but you became so big, and the castle was damaged enough as it was, you decided to stay on all four for the time being.
While you were looking at your new body and how it worked, your father had unsheath his sword and seemed about to attack you, what will you do?