Neighbour girl advice!!

ok ive tried to pick my brain to figure out how to be subtle or pretty much ask/find out/know 100% if the neighbours daughter wants something with me. without making it clear as day or weird between us if shes not. she always talks sexual around me when its just us 2 alone. asked her one day if its only with me and she said yeah only with me she talks that way. she also told me she don't tell her mom anything we talk about. plus she admitted she only says bad stuff to my face so its not on her or my phone.
week ago she was over. just us and was sucking on popsickle like giving a bj. I didn't notice till she was laughing and she just kept doing it knowing i knew what she was doing. she also sent me a picture of her doing it after I knew what she was doing while sitting in chair beside me.
she was on my boat once and went down to a bikini, asked her to put her shirt back on and she smiled, laughed and said no. im a guy shes had to of seen me looking many times.
other day she walked by. just us again and smacked my ass. not hard, like a tap and just giggled.
shes much younger than me plus heres the thing. I can do this in a way itd make it awkward if shes not into more so to say. if she told her mom it most likely make it weird and awkward since they live few doors down from me. plus I don't want that with the girl if its a no either. she always says she don't tell anyone what we talk about. and I don't either cause shes always kinda sexual with me face to face.
she always calls me her brother too. mainly cause I always help her with things and I live so close I think. but these things seem either she wants something or is too comfortable around me and says whatever.
I need to figure this out badly. if shes wanting something I need to know 100% before trying or saying anything to her directly. I want to know so I can stop thinking about it when I see or talk to her. or mainly if she is into this I want to be able to see what happens cause shes very attractive.
any advice? things to ask? or to try? any help would be nice!
Please help!!!!