Part of my essay in English. Could you, please, tell me my mistakes

Once my teacher said: “If you have found something you can do for the rest of your life, no matter what you are paid or rewarded for it, you have found your vocation”. I agree with this statement, that is why it has stayed, memorized, in my mind till the present moment.
When I was a child, I knew that when I became an adult I would prefer to do something big and meaningful. I thought that a life, furnished with success, was the only thing which worth living.
One of the first dream jobs of mine, of which there were a great number, was to be a cashier in a shop: to measure fruits, vegetables and, especially, sweets. Every time we went to a shop with my mother, I stopped and stared at the woman who was measuring sausages. My mother murmured and nagged that I was making the process of shopping much slower. In addition, I liked the way the scales looked. Of course, my parents noticed that it attracted me and gave me toy scales as a present for my birthday. I was so excited, one can hardly imagine. But, unfortunately, I broke them. Later, I realized that putting a watermelon on toy scales was not a good idea.
What is more, there were times when I was convinced that I was very much into bossing my toys around. They were calm and obedient. I wanted to feel more important and take my own responsibility in the way I supposed it had to be. The list of my job descriptions was an easy one: to employ a toy for a job, to find out that it worked badly and was unable to cope with the problems, to throw it out of the work and, eventually, to forgive it and hire again. In the future, I would prefer not to work for a slave driver like my childhood self.
I must mention one more fact. I remember my strong wish to have a pet; also, I remember my mother always refused point-blank to buy a kitten every time I asked about it. Therefore, a huge number of refusals caused my new ambition to become a shop assistant in a pet shop. It could give me an opportunity to take care of animals and to be responsible for someone’s life....