Growing Up With an Older Sister

Glad I found this website! I think my story is kind of unique so I wanted to share.

When I was younger I was forced to share a room with my sister, who is 3 years older than me. We lived in a small house with only two bedrooms, so it wasn't by choice. We each had a bed and a desk, the desks were side by side below the beds. I wasn't really bothered by it at first, but my sister hated it. She would always force me to go do stuff downstairs. 

Anyways, I really wanted to have the room to myself sometimes. I would knock and try to come back in and I would find the door locked. I would yell for my sister to open the door and she would come and yell at me to come back later after she was done "with her homework". One night I was trying to get back into the bedroom and she came to the door and I noticed that her face was really red. I asked her why and she just said it was hot. I noticed something weird then, the front of her gray tights were kind of wet. I pointed it out and she just told me to go away. I said no and wouldn't let her close the door. Once I was inside I wouldn't leave and my sister got really upset. Now I know she was probably frustrated that she couldn't finish what she started.That night we argued a lot as we laid in our beds. I remember falling asleep and hearing my sister still playing on her phone. I woke up later in the night to some kind of rattling noise and was kind of scared at first. I saw that it was my sister, out of her bed standing by her desk. Her desk stopped making the noise and she let out a breath, then I think she pulled up her underwear and went back to bed.

The next day I told her that I saw her last night. She acted like she didn't know what I was talking about. I asked her to tell me what she was doing or I would tell our parents she was weird. She just said " humping my desk, duh. I do it a lot." I told her she should just let me see, because I was really curious if she did it a lot. She told me she does it at night and in the room alone and I could watch with the lights off. We went up to the bedroom after we got home and she took off her pants and underwear (We were both ok with nudity, part of growing up in an asian household), and sort of leaned her crotch on the corner of her desk. She moved side to side and lifted both of her feet into the air. She looked really strained but like she was enjoying it. She stretched her legs and held onto the desk, I remember her butt clenching and she let out a sigh. She rubbed her crotch on the corner a bit more and said something like "still not done." She lifted her feet again and her face got really tight, her eyes were shut tight and he teeth were clenched. She let out a moan and stayed against the desk for a while. I was sort of in shock. I remember feeling really nervous and excited. I had never seen anything like this. She said "there, that's what I do all the time." and said she won't hide it now. 

There's more to the story but that's  how it started. I'll share more later.