Undergraduate / Sister was diagonozed with leukemia: Significant life experience; NYU, USC, UMIAMI [4]

Background info: Applying to USC, NYU, and U of Miami
Warning: Anyone thinking of copying and pasting this essay, be aware that when you use a health related topic like this admissions require you to provide a doctor/hospital letter of proof!

I appreciate any feedback! Especially grammar help..

I do not believe it is a coincidence that many of the world's greatest people ascended to their power, and achievement from lives plagued with tribulation. Rather, I believe, that adversity, however harsh it may be, has the power to propel people forward from ignorance, have them take action to where they've experienced injustice, and allows them to see what is truly important in life. Paul McCartney's mother died when he was only fourteen, and instead of succumbing to depression, he wrote legendary songs like "Hey Jude" and "Let it Be" to help others in their "hour of darkness". Rosa Parks lived under the racism of the Jim Crow laws, but never let their messages of hate deteriorate her spirit. Instead they empowered her to "sit" for civil rights. So, when I was told that my family needed to move from Canada to Tennessee because my younger sister needed a bone marrow transplant, I thought of these heroes. And, like them, I knew that I couldn't let this tragedy defeat me. I swore to make this affliction serve a greater purpose not just in my life, but also to other families stricken with cancer.

The first time my younger sister was diagnosed with leukemia I was in 8th grade and she in 6th. We were only able to keep the cancer away for three years before she relapsed in 2011. Despite the day of her re-diagnoses being the vilest day of my life, it provided me with an invaluable epiphany; life is precious, and you cannot take a moment for granted. It was this insight that enabled me to endure faking my happiness in high school while watching my grades dwindle under stress, rubbing my sister's back and consoling her as she wretched over buckets, and having to forfeit a year of my youth when we moved countries to receive specialized, more intense treatment. Now, I feel obligated to let this same enlightenment guide me through my future to help others. Undeterred by how much I have to study, struggle, and sacrifice I will devote my life to either researching, or working in the field of pediatric oncology. Because even though my sister grows healthier each day, there are still too many children without such positive prospects. And whether or not I am related to them, their lives are too precious to be taken for granted.

Unlike Paul McCartney or Rosa Parks, I will probably never have a platinum album or statues erected in my honor. However, if I can one day look at a child and know that he, or she is able to live the full life they deserve because of my devotion, I will feel just as glorified. And instead of looking at my past with disdainful eyes, I will be able to thank it. I will be able to thank cancer for not only making me a stronger person, but for leading me to righteous future.

(490 words)

My main insecurities are that I somewhat fit two morals into my single essay. Both with the "heroes" and with my "epiphany". I feel that it isn't very clear that it was my epiphany that allowed me to overcome my adversities.

Thank you! <3