I have NC for this, I'm not sure why.
At 13 I was definitely very boy-curious, had kissed and really wanted to be noticed. I thought I was quite mature for my age, but I wasn't. I thought I became sexually active at the age of 14.
I went on holiday with a friend, her sibling and her parents (my first holiday without my own parents). My friend and I 'chatted-up' some much older 'boys' in the park and we were invited to a party. We lied to my friends parents, very easily got away with it, and went to the party. When we got to the party, we told them all that we'd lied to sneak out.
Anyway, I danced and drank (for the first time) and was having a ball! People were taking drugs and one of the people from the park gave me a pill. I got 'ill' quite quickly and he said I should go lie down, took me up to a bedroom, tucked me into bed and left. As he walked out the door his friend came in, got in to bed, kissed me a couple of times and then had sex with me. I don't remember resisting, and I don't remember speaking at all. I remember the pain. In my mind I was saying 'no, stop, I don't want to do this', but I don't think I said one word out loud. I think I just lay there. Afterwards he talked a bit about what my parents would say if they knew what I was like and what would my friend's parents do when they found out we'd lied. Then he said that I better just hope that he could keep a secret or I'd get into trouble. Then he left. I stayed there for a long time, hours maybe, till my friend found me and we left.
I spent a long time terrified someone would find out and then my parents and my friends parents would find out that I'd lied and what I'd done. I never told anyone. It was years later ... many years later ... before I realised that I hadn't been 'sexually active' at fourteen after all.
[and yes, I know what it was, people don't have to say]