I took the ACT and as usual, did very well with the written/verbal sections and poorly in the math, even with extra tutoring prior.
I think the ACT was one of the things that got me into the remedial math class in college which I also failed.
BUT - that's me - there are others on here who have math LD but also have stronger math skills than me. Hopefully they will have more advice for you.
I wish you the best of luck on your test!