When I began my work in engineering, I had discussions with my mentors about many things. Often this was over a lunch where there was a lot of hollering and laughing going on. They told me that if I was using anything more than a plain scientific calculator to get rough answers, STOP! I'm probably doing something wrong. Someone before me has probably encountered this problem and has a shortened rule of thumb that will get to the important conceptual notions.
And in 29 years of working as a Technician, Programmer, and Engineer, I have to say, they were mostly right. There were a few instances where I actually did find a use for the higher math classes I attended.
That said, the conceptual basis for what you're doing must still be learned. I may be able to work with the nulls of a Bessel Function using a calculator, but that's only because I know what a Bessel Function is. So, although you may be struggling with your math course work to understand what is going on, know that these concepts may show up in some unusual places. No, you'll probably never have to derive an equation more than half a dozen times in your career. If you are deriving equations, BE VERY VERY CAREFUL! Check your work in multiple ways, have some intuitive notions of where you expect the answers to be. If you don't know this or you can't imagine what's going on conceptually, walk away from the work.
This is not some abstract word problem for your math teacher to grade you on. Someone's life or limb may be at stake. You have an ethical duty to understand the fundamentals and the mathematics behind everything you design. You need to understand the forces, energies, and materials you use. You need to have answers for every design decision. As such, you do need to understand the concepts behind the math, even if you're not all that good at the precise derivations behind it.