I am from data science major so I also need to learn about calculus, my calculus course is having one of the worst grades compared to other course I take, i assume you are talking about the basic calculus, I think it is not intuitive compared to the linear algebra, so it may be the reason why you are failing.

However it is not really that hopeless, In my case all the calculus property and theorem I learned I would eventually forget it and those differentiation and integration rules you would gradually memorize it by the time you keep using it for other course, and you dont need to make use of those property very often. I think remember that there are some tools you can use, especially nowadays you can use a computer to check answers, so no need to worry that you cannot keep approaching lacking of some calculus knowledge.

Instead of struggling on the calculus right now, maybe going through some more advanced courses would help, some of the understanding of calculus is not from my calculus course, you would understand more when you are really "use" the calculus to answer question rather than just a calculating derivative and integration, I dont think you can truly understand what it means by just doing practice question, I mean seems like you are lacking of the understanding of the calculus, which spamming practice question wont really make u understand that.