Is this speech natural? The janitor-like deputy head

Talking to the deputy head is a real mental.
This week was staff's working week and students who didn't attend the class will have not enough credits and come to do the work teacher assign them to do on staff's working week, I went to school to ask the teachers what I had to do, I hadn't got enough credits and the teachers assigned me extra work. After I've got the assignments to do, I decided to study for my resits because I'll do the assignments when I'm home so I went upstairs to the classroom because the cafeteria was too distractive to study. The classroom was left open. I went there, locked the door, turn on the classroom projector and study on YouTube for my Fs. After a while, I heard a sound like someone was fiddling with a keychan, trying to unlock the door so this had come to my realisation that it was the teachers and I was screwed because we weren't allowed to use the classrooms on staff's working week. To avoid trouble. I didn't open the door. I waited until the sound of the footsteps had gone and ran out of the classroom swiftly. Unfortunately, while I was on my way downstairs, the teacher was going upstairs and... Snap! She saw me. She asked "What are you doing in the classroom?". I lied to her by saying that I was looking for papers to do the work. She asked me whom I came with. Again I lied by saying that I came with my friends. Then, she asked if my friend was boy or girl. I said boy. She asked where he was now. I said he ran away. So she told me to wait but I didn't, I went to the another classroom and continue my study. Until 11:50. It was registration time and I had to ask the deputy head to give me his paper to sign my name to ensure that I had attended. He asked me why did I went to the classroom and I said that I was looking for papers to do the work. Now he told me that it was not good to go into the classroom. He said that I was lack of courtesy and ask me where I was in the morning. I said in the canteen. He didn't believe me and said that I lied, the staff members were looking for you and didn't see you sit there. After answering his serveral questions. Then, I said whatever if you didn't believe me and the deputy head was acting like mocking me for shrugging shoulders at him and didn't listen to my response and ask the same question again and again so I decided to walk out and headed back home.