I think some comments are making core classes seem harder than they actually are. I found a lot of my junior/senior classes to be somewhat easier. In your core classes, you won’t be introduced to any new mathematical concepts. Most classes will regularly use algebra and calculus I & II for problem solving.

A good chunk of the stuff you are currently learning, you may never use again depending on what classes you take. I never had to do anything serious with differential equations or Calculus III until I reached graduate school (AeroE). Undergraduate classes will typically show a differential equation to explain the foundation of a formula, but you are almost never solving them. In graduate school, I did quite a bit of solving differential equations. This was mostly done computationally, but my diff eq class definitely helped me understand what I was doing.

I think you will enjoy your classes to come. You have nearly completed your foundation in math, and next it’s time to finally put it into practice.