Hello Bunzie,
Yes, I totally agree. Online test didn't help me either and it looked like I got the most difficult set of questions. They have a large pool of questions so if you are lucky you can get easy set of questions.
But yes 1 thing happened because of those online practice test. It boost my confidence as I practiced them unless I got 100 in each. I used the below mentioned websites and mobile app.
You will be fine if you read book at least 2 times.
You have 18 days more but please take it as 15. Why? Because many candidates have faced issue while logging in to their tests. So if you do it on 17/18 it will come on weekend and they will respond you on Monday after your test duration expires. That's my 2 cents.
In addition to that, please know that before the test starts, you need to take picture of your Photo ID (Drivers License is the best) and yourself. You need to take picture of photo ID without showing your face in the pic. It's one of the most unusual experiences you might face.
Please don't hesitate to ask further questions.
All the best!
Websites:
https://www.apnatoronto.com/canadian-citizenship-test-practice/
https://www.torontopubliclibrary.ca/new-to-canada/citizenship.jsp
Apple itunes:
Canadian Citizenship Test Prep
http://itunes.apple.com/app/id1106315106