A normal 15 year old girl would not be in the position she is in.
You do not realize how much danger you are flirting with. I would rather be in an old horse-drawn buckboard hauling nitroglycerine over a bumpy rocky narrow curvy mountain pass than be in your shoes.
I saw a youngish woman interviewed one time after she had a guy charged with such illegal activities as you are currently evidently dabbling in, many years after the relationship had ended. She had found love, gotten married, had a daughter and one day she said she began to wonder and even worry what her daughter's teen life would be like, since it is difficult for many teens. She thought back to the older guy she had a relationship with and for the first time she say it totally different than she had in the past.
She realized that she was an immature naive child at the time and saw the guy as an adult who should have known better and should have said absolutely not, but who instead took advantage of her thinking she was pretty much an adult and able to make the best decisions for herself. Then she started to think what she would do if in the years to come her daughter ended up meeting a guy like she did and ended up in a similar relationship.
For whatever reason or reasons this little girl likes you now she will age and mature and in the future she may see things very, very different than she now does. She may see the guy that right now seems to be on her side, a help to her, someone supportive of her, someone she can depend on, someone who loves her as just being some older guy that saw a weak easy mark and wanted some young tight stuff so he manipulated her and used her. I am not saying that is what you are doing, but in the future that might be how she perceives it to have been.
If that should happen one day, the next thing to happen could be you finding yourself in a prison chapel getting hitched to some 350 pound guy named Bubba, and then going on a 10 to 20 year 'honeymoon.'