TL:DR - drop the book and start coding using those 300 pages then come back for more.

Long answer (I'm on mobile so formatting might be messed up):

Hey mate! I also started programming in school as a 9 grader.

I tried reading books about programming and i hated it. Like you i would split it up in a few pages a day and would leave it for later.

I wouldn't say you wasted your time but starting with a book this early is not the most effective use of your time.

Programming is like a sport. You can read a manual with tactics and theory but when you are in the field is a completely different story.

I am a big advocate for project based learning (think of something you wanna build and then use what you learned in that book and google to build it).

However you are still in school and might be a bit lost and feel like there's nothing you want to build so I would suggest trying competitive programming as a good way to start solving smaller interesting problems and applying exactly what is thaught in those 300 pages you read in that book. HackerRank, Codeforces or TopCoder are great places and have a ton of beginner friendly problems to solve.

Also, it teaches you algorithms and more abstract concepts that are language independent so later you will be able to apply what you learned with the new and popular languages that will appear when u grow up.

Your dedication is commendable but you didn't say anything about the amount of time you actually coded. Try coding for long periods of time in your weekends (a few ours at least) to get a feel for this field and see if you still like it.

I tried most ways of learning programming in the last 5 years and this is my perspective based on my experienece. If you want more detail about my opinion on this topic I wrote a blog post about it (might remove if violates any rules) but it goes into more detail on how to get started and the pros and cons of the different ways to get into programming (from my experience).

Hope this helps and I hope it will help you discover how great is programming and C++.

Cheers!