Struggling Step Mom

I don’t have kids of my own, but I did however marry a guy with an 8yr old girl who was staying at my husbands grandparents house for the majority of her life and they spoiled the living hell out of her and turned her into a little demon.

I love the little girl to death but I am VERY uncomfortable with the hugging and affection like that towards her or anyone except my husband really. Does that make me a bad person???

Also, when I discipline her, she laughs (literally and figuratively) at me which I cannot stand. And she will not listen for crap.... my husband works on a tugboat 28 days out of the month and it’s just me and her here at home...

And with school letting out, idk what the hell to do!!

Would me having my own child (if I was to have one) have any effect on the situation? I’m just wondering because we have thought about having one before but idk if I do if this is what I have to look forward to AGAIN

HELP?