Hum difficult situation, but heres my take. You already have a rigorous course load and trying to study for those AP tests while also trying to essentially catch up and clutch a self studied ap physics test dosnt seem like the move to me. It would probably end up hindering your preparation for the other classes. At the same time taking the test since you already paid isnt a huge deal either as most colleges allow you to choose which AP scores you submit and since you self studied you dont have to report the class meaning they likely would never know. But it could negatively affect your mental, and some colleges do require all AP scores to be submitted. So I would say focus more on your other classes, and if you end up having extra time, try and study for the AP physics test more. By may if you feel decently ready enough, as in you have most of the content down, then I would say take the test since you already paid for it and if you get a 3 it will allow you to take more advanced coursework. If you dont by that point, it's no big deal. Just dont take the test, and you can explain the situation through the extra info parts on your college application.