Undergraduate / "Being a Mother." - world you come from (family, community, school) [7]

Hello :)
I need some feedback for my UC prompt #1. It's my first draft, and is very rough.
I really appreciate your help. Thank you!

Prompt #1: Describe the world you come from - for example, your family, community or school - and tell us how your world has shaped your dreams and aspirations.

I am the mother of two children - not literally, of course. I mean I have two siblings of whom I play the role of a mother. I have a younger sister, now a junior, whom I still have to wake up every morning. And I have a baby brother, just turned one in this June, whom I have to chase after until the bed time. Out of many roles I play in my life, the role that has been most inspiring to me is that of an older sister, or a mother, to my siblings. This role is truly the one that has stimulated my interests to grow toward the medical careers in which I can practice a thorough motherly role.

When I and my sister Dominique came to live with our grandparents, she was three, and I was five. We were thrust into the situation we were not prepared for: living within the absence of a father and a mother. Our parents' divorce brought that much of the responsibility to take care of my younger sister, a task which was yet too burdensome to be dealt by a five year old. Since then, I was not only an older sister but also a mother. As Dominique entered school, I woke her up, dressed her up, and walked with her every morning. I always had an extra set of materials she might need in class, picked her up after school, and checked if she completed her homework every night. Every time I had to refuse my friends' offer to go outside and play because of Dominique who since then grew too strong attachment to me, I blamed my parents who had laid on my shoulder too much of obligation. It was a tiring job, I admit it. However, although it may seem unusual to hear, from some point of my life I began to take pride in the role as both a sister and a mother. I take pleasure of being accommodating, committed to helping others, and able to sympathize with others. I am now also aware that there is no reason to take the parents' divorce merely as a painful memory. I can take it as a valuable opportunity that has allowed me to grow into a more mature human being, and to discover my passion to pursue medical career that entails my motherliness.

It has now been more than ten years that I have taken the pleasure in playing such a role. Just as I slowly began to feel anxious of being taken away this thrilling role due to my father's new marriage, my step mother gave birth to my baby brother, Dan. Again, I am delighted to be given a chance to re-play the role I am proud of. I do not mind waking up Dominique every morning, or chasing after Dan until he falls asleep. They are more than welcome to.