My sister has been talking about moving out of state and now that she knows I'm pregnant she wants to move faster because she doesn't want to be an aunt to my child because I was "never an aunt to hers"

I was 11 when I became an aunt so it's not like I could do much or was overly interested in a squealing baby but as I got older and got my drivers license I became there personal taxi service my sister made me go pick my nephew up from camp 3 hours away because she was to busy! I also took my niece to day camp and stayed the whole day with her because again my sister was busy.. I've taken all 3 of my nephews/niece to many dental appointments to and from school etc my niece text me first when she got her period and text me when she's sick or her mother is making her cry. Many times my niece or nephew have complained about neeibg new clothing items because there mother won't buy them so I buy them shoes and underwear pants shorts whatever they need ( they may frequently be from goodwill but there the best I can find ) ... I have never been an aunt to them ?? .. How could a human being deny a child simply because she thinks I wasn't a good enough aunt to her children