My Short Story (in Progress) about A Girl Who Travels into Another Realm

Brielle stared at her reflection in the darkly-lit bedroom on that brisk October evening, thinking about the day's events. It had been a fun, but busy day. It was the night of her birthday. Her parents and grandma had come over, along with her best friend Renee, to sing Happy Birthday and have cake and ice cream. It was hard to believe that Halloween was already next week. She had originally come into this bedroom to get her Halloween costume out of her mother's closet and try it on.
Now, standing in the light of her mother's lavendar rose candle in her Marilyn Monroe costume, she barely recognized herself. Her pale skin gleamed in the limelight, but her dark curls were hidden by the blonde Marilyn Monroe wig. The white dress was a little long on her petite frame. She would need to get that hemmed. Maybe Mom or Grandma could do it for her within the next couple of days, she hoped. As she stared deeply into her own hazel eyes reflecting back, suddenly her own pupils seemed to flash fiercely in the mirror. For a moment, it was as if someone entirely different was looking at her through her own eyes. She shook her head vigorously and blinked. She must be seeing things. Twenty-two and still living at mom and dad's house, and a recent college grad at that. Yet, here she was, still not on her own, with no job, and no boyfriend. And now she was imagining glimmers in her own eyes that creeped her out. Wow, thought Brielle, I've really reached a new low. She was just about to turn on her heels and walk out of the room, when something else in her reflection caught her eye. It was a discrepancy. There was a book sitting on the nightstand in the reflection, that was not there in the room with her. But that couldn't be right. Brielle couldn't trust herself. She looked back over her shoulder to be sure. But the nightstand was empty. There was nothing on it, except the lacy doily her mother had crocheted herself. No, in the reflection of the mirror, there was a book on the nightstand. It was a rather thick volume, but she couldn't make out the title, and as she leaned in closer to get a better look... Somehow Brielle fell, down, down, down, through the mirror, perhaps, she wasn't sure.... but suddenly, her body did a somersault and her head hit the laminate floor, hard...
When she came to, she was in the same room... Or was she? There were slight variations. She was still in the Marilyn Monroe costume. Several of her dark curls had popped out from underneath the wig, which was now on sideways. Her lips, which were only adorned with chapstick earlier, now seemed tinged with bright red lipstick. As she came to, she realized the room was reversed. Everything had flipped. Plus, things were added... There was a rug in here that was not in the original room. It was blue, grey and black, and very expensive and ornate looking. It was not her mother's taste. There was the book on the nightstand. As Brielle made strides toward the book, to get a look at the title, she was suddenly gripped with fear... What was this strange realm she had fallen into? She had an eerie feeling that the book might be connected to it all. Was this all some kind of crazy dream? Would she wake up, and her Mom and Grandma and best friend Renee would be just downstairs, laughing and licking the frosting off her birthday candles and joking around as before? Brielle was terrified to look around or open the bedroom door, for fear that something really strange had indeed happened. She couldn't summon the courage to glance at the book. Not yet. But she stepped every so gingerly toward the door... and as she did, suddenly, the knob turned from the outside... the door was opening... and Brielle was terrified to see who or what was on the other side.