I think my little sister (12) is in love with me (17)

I'm not sure if its that she's developed feelings or that she's just reaching puberty and is experimenting but she regularly tries to cuddle and get close to me now. Ive put a full stop to any "naughty" interactions( she has tried to get me to engage in sexting and even masturbation races). I just don't think it's healthy or right for her to get involved in that stuff yet. Ive tried setting boundaries and getting her away from me but she just always tries to get close anyways. I'm not sure what to do.