Try breaking your studying up; instead of trying to accomplish large amounts in a certain time; just do little things. Whether that be read a chapter of a text /source, make a summary for a single dot point or something like that. Trust me, I know what it feels like to drown in the copious pages of notes for these humanity subjects; so try breaking everything up.
As you would probably know, the ATAR only requires 10 units (2 of the being English), therefore you have the flexibility to drop at maximum 3 units.
If I were you, I'd be discussing this issue with others, whether that be parents / friends / teachers / etc. Mainly because, once you're in this mindset of 'I can't do it, I'm struggling, I'm sinking" it's difficult for clear decisions to be made. So talk with your teachers about your progression in your subjects, maybe discuss a few strategies to help combat the heavy work load. You do two extension subjects, so I'd make sure in the least that you talked to your teachers of those extension subjects about the trouble you're having. Particularly your Extension II English teacher, and if they think it would be best to drop EE2 then considerate it.
Try not to stress to much. If you work hard throughout the year, there 'shouldn't' be too much to panic about at the end. Keep your head up, stay strong and best of luck! : )
