Disguise yourself as a guard

Tearing off your top and what's left of your skirt, you reach for the smallest set of armor you can find. It is an outfit made mostly of thick leather, except for a few metal studs along the hauberk and the gloves, but it covers all the important bits, so function isn't as important. You pull the leggings on, finding that they fit rather snugly against your ass, and then the chestpiece, which fits much looser around your body, being made for more broad-shouldered males after all.

You then look around for a helmet that would cover your face. You find a full helm that covers both your head and neck on a suit piece farther to the right. It also has a face piece that can be closed and opened, leaving little more than an eye-slit when closed. Perfect for the job.

Now fully dressed as a guard, you step out of the room to try to make your way to the main floor.

You pass by several other people, some of them girls, some of them customers. None of them even look in your direction. You make sure to avoid coming close to any guards though, for surely they would recognize you immediately. After half an hour of weaving through the brothel, avoiding patrols and fruitlessly searching, you finally make your way to the top floor of the Palace of Infinite Pleasures, where you think the princesses live.

But now you are stuck. You have no idea which room is Elena's. There is a lone guard on-duty here on the top floor. You could risk asking him, and hope he doesn't recognize you, or you could just knock on the nearest door and hope for the best.