Helen, you are SO not alone!
First, thank you, Helen for bringing this out into the open. You know, it seems to me that it is only 'society' that sets the rules. Deep down, we are basic pack animals.
This happened when I was 15. I got used to having wet panties most of the time from the age of 12. When I started to develop, along with my breasts which as still only 34a, the most visible sign was my vaginal discharge. I am wet as a matter of course, when I am horny, its like Niagara falls!
When I was 15, I remember feeling horny almost all the time. I would hump my pillow, or the arm of a chair. Sometimes, when I was fooling around with friends or family, I would 'accidentally' get into a position where my pussy was rubbing up against someone.
Anyway, to the story. I was 15, we lived in a really small house and my folks had friends visiting. This meant that I had to share my brothers room. That was ok because he's really cool. (older than me) Oh yes, our house had a really shit heating system and this happened mid January with like ten feet of snow outside. So, there we were, clearly able to see our breath in his room, and all I had was a sleeping bag on the floor. Mike said that I would freeze my ass off down there and I could share the bed. I snuggled in beside him and as I did, it suddenly felt very grown up, being in bed with a guy. I wriggled down into the bed and said 'Mmm in bed with a man at last... be gentle with me!' Mike laughed and played along. He rolled half on top of me and said 'Be gentle? No WAY, I'm going to fuck you through the bed' He half pretended to move up and down and it was really very funny. Trouble is that in the blink of an eye I was so turned on and I started to pull him on top of me. He also had stopped laughing around and was suddenly between my legs and I could feel his hard on against my panties.
I remember clearly wrapping my legs around him and pulling him tight against me. I also remember saying 'Oh fuck.. don't stop... make me cum.' He started rubbing up and down me like crazy and I felt myself cumming. Mike grunted too and suddenly, I felt something splattering on my face. Mike had gotten so hard his cock had slipped out of his PJs and he had cummed so hard it hit my face! The first time I had gotten anywhere near sperm! It felt so lovely, and smelled so nice too. Mike was embarrassed, but I told him I loved it and it was ok. I cleaned up using some tissues, and we drifted off to sleep. At some point in the night though, I woke to find his arm around me and his hand on my tummy. I put my hand on his and gently guided it between my legs. I knew my panties were warm and moist from earlier. I made his hand cup my pussy and then I started moving it a little. To my delight Mike must have woke up and he carried on for me. I reached over for his cock and jacked him slowly while he rubbed me to another lovely, but much smaller orgasm. I told him I wanted to actually watch him cum, so I got under the duvet and carried on jacking. He suddenly said 'Oh sis, I'm cumming.' and I got to watch as he shot his load onto his tummy. It was nothing like as much as earlier, but still it was neat to watch.
Since that night, we have fooled around with each other from time to time. I've let him watch me masturbate, and he has let me watch him. I also discovered how much I like talking dirty and being talked dirty to.
I hope Helen that you find more girls who have had feelings like this, because somehow I don't think you are alone at all.