I don't see how one can get trolled over it, if you go "LOL IM JOKING" I really wouldn't care less.
It's really up to you. I don't know why you're freaking out. Technically you have nothing to worry about because you're the minor and you can say she's coming on to you.
You have two options here:
1. Wait till you're 18 and just relax and tell her.
2. Get it on.
Legally I suggest option 1. Also calm the forget down you aren't going to get arrested for being a teenager being seduced.