I would pay to impregnate my little sister

Hi, I’m 18 and my sister is 17. I really want to impregnate her. She’s said she would sleep with me but she doesn’t think a family baby is a good idea, but I really want to be a dad and I’m a little autistic so I don’t know if I would be able to get a girlfriend. So I’ve been trying to convince my sister to get pregnant. I even offered to pay her $1000 to be my baby momma, but she still said no. What can I do to get her to say yes?