Doppelganger In The Mirror

I was staying at my Aunt and Uncle's house for the weekend. Upon entrance to the house, there is a small room. To the right is an entrance to the living room, while there is an entrance to the kitchen across from it. The kitchen has the only door to the backyard within it. If you look straight from the front door, there is a set of wooden ladders. After about 10 steps up, the stairs stop and continue to the left. If you follow to the left, you will come to a hallway after passing some more steps. To the left side of the hallway is the master bedroom and bathroom and on the right side is my cousin Drina's room and the guestroom (where I stayed over). However, if you follow to the right, there is a wall-sized mirror that I particularly dislike.

On the first day, nothing really happened, but at about 10pm on the final day of my stay, (Sunday) my cousin asked that I didn't make much noise because she had to wake up early for a basketball game in San Antonio. I nodded and told her that I was going to sleep anyways, and went back into my room. I was awoken by the noise of someone opening their door, and I thought it was my cousin, so I rolled to the side and checked the clock. It was 4:30am and, even if it appeared too early, I wanted to go say goodbye to my cousin. I put on my glasses and headed out the door. From where I was, I could see the mirror across from the hall. At first, I thought my cousin was standing over the mirror in her team's uniform. I was going to go greet her, but I stopped and realize it was not my cousin, but her reflection! I read the name of her team imprinted in the shirt. It was backwards, like a reflection itself. I hurried over to my room, shut the door, and hid under the covers. That THING had scared the living daylights out of me!

At 10am, I woke up again. This time, I saw my 'cousin' again. However, it was not a reflection. I thought it was her this time, but I focused on the team's logo. And knew at once that it was a doppleganger.