Please check this essay. i am an asian, so please tell me if i made any mistakes

What is your intended major? Discuss how your interest in the subject developed and describe any experience you have had in the field - such as volunteer work, internships and employment, participation in student organizations and activities - and what you have gained from your involvement.
When I was six years old, I used to play a game with my friends in which I always choose to be a doctor. I always enjoyed playing a doctor's role, but I never thought that it going to be my intended major. The real interest in this field developed in college, and by volunteering at Bel Haven Care.
When I entered in Fresno City College as a freshman, the first thing that I did was made an appointment with a counselor because I was unsure about my major. I told my counselor that the biology has always been my niche and I want to make sure that if I had made a right choice about taking biology courses. My counselor looked at my school transcript and told me that I should give it a try. After consulting with my counselor, I registered for "Biology 1" class in the hope that it will take me one step toward my aim. After taking that class, I actually realized that this is the best career for me. I started enjoying learning about how the lives of all humans, animals, and even plants revolve around biology. I was fascinated to learn about how different parts of body work in an astonishing ways. My biology instructor, Mr. Rodney Olsen, also noticed my curiosity toward biology and suggested to do work hard to fulfill my dream. He told me that this field is very competitive and it will take lot of effort to get what I want. He also suggested me to do some volunteer work which will help me to gain experience in this field. This is how my interest in this field developed.
As my interest in the biology field developed, I started to become conscious that now it is time to take another step toward my goal and that step is volunteering. I looked for a volunteer work in which I can get a chance to help other people. After looking everywhere, I got my ideal place to volunteer. I became a volunteer at Bel Haven Care where my task is to help senior residents by taking care of their nails and by cleaning up their rooms. I had gained two most important things while helping them such as the sense of responsibility, and the happiness. While volunteering at Bel Haven Care, I learned the true meaning of responsibility. It is not only about making decisions that fulfill my interests, but the interests of others also. I learned that the doctor's most important job is to make sure that he/she is fulfilling the requirements of their patients and the doctor who succeeds in doing so is called the superior doctor. Not only the sense of responsibility, but I gained happiness also which I got by helping other people. As Norman MacEwan wrote, "Happiness is not so much in having as sharing. We make a living by what we get, but we make a life by what we give."