Is it bad that I'm finding Calculus to be a serious challenge?

Particularly as an aspiring Math teacher? I've got a high B in the class and am doing okay on the homework, it's not so much the grades I'm getting as much as I just feel slightly overwhelmed. I understand that it's normal for Calculus to be challenging, but as a teacher, with Proofs and Linear Algebra etc. coming up, I feel that Calculus should come more natural for me. Any feedback would be greatly appreciated thank you!