A or AN?

Hello, my dear friend. Nice to see you here again. For today I've made green tea. Have you ever tried it? I'm gonna get A cup for you. I am AN amazing boy, am I not? Hahahaha! I'll be back in A minute. Turn on the TV, please.

Hey, I have some doubts about using A or AN on my writings. Could you help me please by correcting this text here?

Susan is intelligent girl who works for extremely big company as its director. She was only 21 years old and already scientist when this story happened. For being an girl some of her men co-workers did not value her work in the company and they sometimes said she couldn't do a man job. And it sometimes  hurt her. The young girl knew she couldn't give up though and  she didn't. She wanted to prove herself she could do anything she wished. Susan worked day and night, night and day. She didn't mind if she looked like tired old lady. She was seeking her dreams. One day the scientist discovered substance which could destroy the HIV-virus in six months. Because of this she won a award from her country and later the Nobel Prize in Science. After two years she became the company's director. At her first meeting as an director, she looked at everybody and said: "Some laughed at me and those laughs made me stronger. Sometimes they hurt me. I didn't have time to mind about them, however. I am what I am. Where is my place? It is where I want to be. What I want? Fair place to work where everybody has the same rights, salaries and the most essential feeling: RESPECT for each other. Thank you.". 

ANSWER KEY >>> http://drinkingteawithwesley.blogspot.com.br/2017/03/a-or-answer-key.html

Is it a game? http://www.englishexercises.org/makeagame/viewgame.asp?id=1203