If the assignment is to describe your most frightening experience, then I see nothing wrong with the amount of time you spend on the accident itself. I think you also relate the after-effects of the accident quite well, too.
I just have a few editing suggestions for you:
Wires started sizzling and sparks
all were screaming hysterically,
fumbling in the
darkness. [I would delete "and managing to make it out." It sounds like you were out of the bus already] The world went topsy-turvy, but I tried to calm myself down [delete "in fright"] by repeating [delete "it"] over and over: it
was just a little collision.
I was too frightened
to think, however;
all I wanted was to get out of the bus and arrive home.
to smell my mother's perfume
Every second I struggled, my nails dug
deeper into the leather of the seat and the more I wanted
After the accident, I [delete "grew to fear" - that does not really make sense] worried that I subconsciously lost some of my
spunk for taking challenges, but instead I started pondering more carefully about the loss
and gain of every action I take.
In negative ways, the bus accident weakened my sense of security and it has
haunted me all through
my life [delete "since after"]. However, it now reminds
me of how strong-willed I am for surviving and how it may have contributed
to my survival in school and community. Each time when I am
faced with a problem, I will approach it with strong will and perseverance, just like the moment I felt a strong desire to live and struggled to find a way out. Meanwhile, I strived to work my best in both school and community. I became a camp counselor in a
boys & girls club and youth center, and
shared my own story while teaching the youths to be resolute and able to protect themselves in danger.
Terror, although it existed whenever I retrospect to a bus accident, I will fight against it with a strong will. - This sentence does not really make sense. Better would be "Although it was a terrifying experience, the bus accident left me with a strong will to fight and survive."
Best of luck in your studies!