FWIW, I am self-diagnosed with aphantasia (I can't imagine any feature of my kids' or wife's face, for instance: I can remember those which I verbalised), and I pretty much excelled in maths and got a BSC in maths and computer science.

However, I want to point out that your repulsion to blood or gore likely has nothing to do with aphantasia: I frequently have my blood pulled for some medical check-ups, and I never had a problem with it, going all the way to being a kid.