I see you got some great advice already, so I'm just going to add that maybe you could try learning from different sources. I can relate to "just not getting it" in a few courses, both in HS and later at university. I also know what it's like to have an incompetent teacher/professor. So what I did in those situations is I got different textbooks that explained what I needed to learn in a different, often simpler way. I don't mean to sound condescending, so please don't take it that way, I know the problem isn't that you're not smart enough I'm trying to say that sometimes it's useful to get a different perspective on what we're studying and that often allows us to integrate the knowledge provided by the teacher. For example there are lots of youtube videos and video lectures that I personally found way more interesting and way easier to grasp than the way I was taught in school.

Just a couple examples of the sites I was using:
https://www.khanacademy.org/science/physics
videolectures.net/Top/Physics/

Hope this helps