Dear Madzter2000,
I'm currently studying Modern History too! (So just a student like you).
But I think while overloading content and information is easy to do, it's important to keep it organised to stay on track.
Like you said, it gets overwhelmingly difficult with both teacher and textbook.
What I normally do is take notes from the teacher but these "notes" aren't study notes as such. They are just in my workbook to layer and consolidate extra information. Since what my teacher does is normally give an overview of the topic and then let us discuss the event or person as a class, it's super interesting for different perspectives and points.
This is what I jot down during class.
But for textbook, I would recommend just reading it. You can make little post-it notes and stick them in important pages you need to refer back to, but textbook is IMAO much too dense to study from.
I totally recommend SYLLABUS SYLLABUS SYLLABUS. These are the only things you will and can be tested on,
Don't throw out your old notes. Keep them handy as an extra but make sure syllabus is your main chunky part.
Extra info on Peace Moves for Changing Attitudes will be great for a unique source analysis when it comes to the exam (as long as they are your notes and not the teacher's for the whole class) go for it!
Furthermore, since I'm doing Nazi Germany later on, I'm finding it useful (cause I'm starting to like history more) to read little excerpts on WWI to keep it fresh and read novels on what Weimar Germany was like.
Hope this helps! It was a bit long, wasn't it?