I would tend to think that maybe she doesn’t remember. I would think that as a beast her human senses would leave her. Charming specifically asked for the beast that guarded the castle. Why didn’t she turn into a dragon when fighting Regina? My guess is because she just didn’t get a chance. With Regina it was magic against magic and in a wizards/witches fight turning into animals is usually left as a last resort. I have a feeling that is why Regina bound her the way she did so that she was unable to turn into a dragon.