Wow! The suspense is killing me. After the the first chapter, I couldn't stop reading it. The elaborate narrative style is good. However, call me old fashion but I think some parts, especially Part 3 and 4, could get more content. For example: How was Georgie coping with the whole situation? Did he panic or did he try to stay calm? Did Abby's mom lose it and lash out on the kids? Did the cat bring Abby comfort?
Secondly, you could leave somethings to be discovered by the readers in between dialogues. Like the name of the cat.
Also, you were really shifting between tones and tenses. I noticed how you used past tenses and present tenses. Maybe using Microsoft Word might help. And the way the protagonist's name was introduced made it sound like a high school speech or tale... something like that. You could reveal the protagonist's name in the dialogues. Although, it's YOUR story and narrative.
P. S. Teen fiction is another tag you could use for the book. Again, it's YOUR story.