It's a lie to say were not all scared of something.
... If you change the order, this would read better with more clarity;
It's a fact that we all are scared of something.For me, this great fear is math.
With me, this great fear is for math.Although it pains me to suffer from such a childish phobia, I can't deny that I, a college bound high school senior, suffer from math anxiety.
I think you need to simplify the presentation.... too much complicated words gives a crowded look for your sentence. The most important thing is that you convey your idea crystal clear to the reader.
I cannot deny that I suffered severely with this childish math phobia.Since my kinder garden days, Math tests have been horrifying events for me
Don't repeat the same idea too much.... Now tell the reader how you recovered :)