Wish I could help you. But, though I majored in Journalism, I have never written further than "Chapter One". :-)
I started writing stories on a manual typewriter when I was a kid. I was a much better writer back then. These word processors have turned us all into obsessive editors. I even edit my emails and posts over and over before sending them. They've also made us lazy, too, because they pick up all the misspellings and grammatical errors for us.
So, try using an old typewriter again, or try writing the last chapter with pen and paper.
Your writing seems very natural. It's always a better read when the writer himself is enjoying the story, too.
If I were you, I would change this sentence:
>>> He knew of only one person that used that knock, but they weren't there. <<<
Either: "He knew of only one person who used that knock, but she (or he) wasn't there."
Or: "Only one person used that knock, but she (or he) wasn't there."
Also, remember the "subjective were" when expressing a wish or desire. Example: "If only he were..."
Maybe you can end the story at the second to the last chapter. Just say you wanted to leave 'em "hanging at the end." ;-)
Thanks... remember, you are critiquing one of a number of chapters.
Seriously. Thanks.