You don't need to be but it sure would help if you were. It would have have helped me get through it if I was but I'm not. My maths skills weren't and aren't as strong as I'd like them to be. Frankly they suck. I have to work extremely hard when it comes to the more complex problems and my dyslexia might have a lot to do with this problem.

I couldn't memorize the multiplication tables because of my dyslexia. Instead I learned to just do the maths in my head very quickly so I have the appearance of knowing them. I use a calculator for everything now but I still can't help doing everything out in my head too. I write out everything and keep all notes and maths for every project. A side effect of this issue is that I have impeccable documentation of every project that I've been involved with.

You don't need to be a math genius. If you decide to become an engineer you can be one. You just need to be determined and unwavering in your purpose. Learning the math isn't that hard. Retaining it is. If you can't retain it you'll just have to learn it all over again and that's not hard. You've already done it before, do it again. Differential equations are rough to relearn every time when you look at them as a whole but that's not really necessary. Break them down into the smallest functions and do the maths. Over time you can get quick at it. It's just work and sacrifice. If you decide to become an engineer you won't have time to do much of anything but study. Maths are the underlying base of everything and if you understand how to do the most basic maths you can do the really complex maths too. It's just work. If your maths suck you'll just have to work harder than everybody else. Work makes you stronger. Be determined in everything you do. If you become an engineer other peoples lives may depend on you doing the job properly. You don't need to be a math genius, you need to be determined that the math you do is right. Every problem every time.