My first time with my sister

This is what I came up with:

This is about the first time we started having sexual games with my sister. Before anything, I'll tell you that we had a 1-year age difference nothing more. At that moment, she didn't have big tits, she had acceptable tits for her 18 years, a pretty firm ass and was very beautiful. I didn't have much physical development at the time, but my tremendous cock was already forming, which I have now. I'll tell you about it in the simplest way possible. We used to play together a lot, we had a very good relationship, we were very close friends, we told each other everything and would often play fights together, both standing up and in bed. I was getting hot with any touch I had with a woman at that time, and my sister was the closest woman I had at that moment. One day we started playing on our parents' bed, which by the way, they worked all day and left us alone, so we would touch each other, pinch each other, and laugh, and my cock would get hard, so it was pretty stiff, not super long, about 15 cm when erect, but already had the thickness I have now, more or less, which is around 5 cm in diameter. So in a moment without meaning to, she grabbed my cock and said: 'Ehhhhhhhh, what are you hiding there? Stop acting stupid and get that sausage out of your pants.' 'I'm not a sausage, it's what I have between my legs.' 'Come on, don't be silly, you can't have that being so young, let me see if you can handle it.' 'You're crazy? Look, am I going to show you my cock? Don't you know we're siblings?' 'Plus, you've never seen a cock before.' 'I'm showing it to you but promise not to tell mom or dad.' 'Okay, let's do this, you show me your cock and I'll show you mine, what do you think of my pussy?' 'Yo: Okay, it gives me a little fear, but it's fine, let this stay here... In progress...