This happened in the summer last year, I was fifteen at the time.
During my school summer holidays, I was very horny (which is typical for a boy of my age I guess) and started to hang out with the girl next door to me called 'S' aged fifteen. (Not real name)
She was about 5'5' with a very curvy figure, a nice ass and about 36B/C breasts. She always wore very sexy clothes and was always flirting with me by 'accidentally' dropping something in front of me and then bending over to get it.
We were very open with each other, and the conversation always turned towards sex and masturbation. After about a week I asked her out and she said yes. I thought this was my chance to have some 'fun' if you know what I mean.
One day we went up to our local playing field and we walked over to the far corner away from any people. As we lay there on the grass 'S' leaned over and started to kiss me. (I was quite shy around girls) She then grabbed my hand and placed it on her breast. I think I must have looked a bit shocked but I wasn't going to disagree, so I rubbed her breast until I could see and feel her nipples become hard. I then sheepishly asked if I could touch them skin to skin. She had no problem with that, so she undid her bra and I slid my hand up her top and started to squeeze and rub her breasts. She lay there letting out the occasional soft moan. By this point I was as hard as a rock. We then sat up with her back on my front while she was in between my legs. While I sat there rubbing her soft breasts I kissed her neck passionately. I then asked her if I could finger her, she said no at first. But after a while she said I could rub her pussy over her pants. I wasn't going to say no, so I slid my hand down under her trousers and started to rub away. She then placed her hand on top of mine and guided me. She started to moan and breathe heavily. Her pants were really wet and you could smell her sweet pussy. Then I noticed her little brother coming over to us. So we had to stop. We both went our separate ways.
I masturbated many times that night thinking about what had happened. A few days later she broke up with me and I was upset about it.
Since then she has moved away, but I still see her at school. But just lately me and 'S' have been hanging out again and we have admitted to each other that we fancy each other, so I should be posting again soon.