@Itjenni I believe most of the country is using the same APUSH text book. What I remember about my son taking APUSH, it is a whole lot of reading. My son loves reading and history and is a fast reader so he skated through. His best buddy is a STEM whiz. Not a big fan of having to read 50 - 75 pages of a textbook a night and would rather be working on math problems than history. Point being, it’s not for everyone and when you enroll in classes for senior year, don’t focus on enrolling in a class because it is an AP class, make sure it is a good fit for you and your academic goals.
Seems you are too far into the year to drop the course. Generally, a school will not let you drop if you are far into the semester but may let you move down to the regular class. Discuss this with your parents and have them schedule a meeting to discuss the possibility of moving to regular US History and a broader discussion on a plan to get you into the right classes. I suspect your statement “APUSH has been affecting me in my other classes too, I have a D in both Alg 2/Trig and AP Language. So, currently my GPA is 2.6. My past grades in freshman and sophomore year has been A’s and B’s and the cumulative GPA is 3.7” is not exactly accurate. It could be that AP Language is also more difficult and time consuming than you realized it would be. You don’t want to go through the whole year with a D in Alg2/Trig and AP Language so be open to moving down to regular Language and USHistory as an option. Do everything you can to try to catch up in these classes. 6 weeks in is better than being 12 weeks in so just get clarity from your counselor on what options are available to you so that you can get control of this situation so it’s not controlling you. Good luck!