OMG math!

I'm normally the one that gets math, i understand numbers, but this year in math "AP Calculus" is about to drive me crazy. I'm in a class full to the brim and it makes it very hard to concentrate, we also have a sub right now that is very sweet but she is learning along with us which makes it hard to understand what she is teaching. the part that scares me is that i have a test in there tomorrow and i have no clue what we have even learned thus far. so i came home and started on all my homework never spending more than an hour on math i ended up spending almost 3 hours reteaching myself and taking my notes from my own book and trying to figure out what it was saying so i could complete the review for the test. I'm just hoping this will be enough to help me do good on this test. i mean I've never had to put so much effort into something I've always been blessed with a great math teacher. i know i have a great teacher but she had to have this time off to recover, and i need time to recover from this studying. i just wish this sub that we have would understand that some of us students didn't want this AP course but had to take it because we couldn't have an accelerated class because not enough people signed up. i think this teacher should allow us to take this test home or at least use our notes because even with my notes on my homework i barely understood what to do right after teaching to myself. this class is just crazy all around and i think it's just too much especially since its not the class i wanted.