IB student, AP physics dilmena.

[IBMaster99]

I'm pretty sure only students in Canada and U.S. might have enough insight to answer this, or give any advice. Anyways, I'm a senior in IB, and I'm certain to stay in IB and get my diploma. Now, I've only had SL bio, and Hl chem, which I'm currently taking. I wanted an exposure to physics so I picked AP physics. In terms of math, I took algebra 2 my sophomore year, took a year off math my junior year for an off period, and now I'm taking IB Math Studies SL. Now the problem is that I'm struggling with AP physics quite much. I don't understand anything in that class no matter how much I try, even though I got a 91 first marking period. I can't move to another advanced class because it's already been pass a marking period, so my options are limited. I could demote myself down to a regular physics class, but that would drop my GPA. I can also take an off period for my 1st period physics class, but that would mean I would have 2 off periods this semester as 4th period, I have an off period. If that happens, I'd have to take a class to replace the off period after TOK this semester for 8th period, and only options for that are regular pscye and AP Econ. I'm taking HL history of the Americas which covers AP Gov and Eco, but if I actually take the AP ECO class, I'd get college credit. Any advice?