help with next of kin?

help! both my parents have passed away, I have a living sister who said earlier to me that she was not my next of kin nor my sister, although she is my sister. I had a son in 1987 who was adopted against my wishes, I have a daughter who lives with her dad, she was born in 1997, I and her father were not married and neither I was not married to my daughters dad, I cannot go into reasons as very personal. I was married in 1979 but divorced in 1983, then I married in 1991 and divorced in 1994, both of those husbands are deceased and I did not have children with them or anything else for that matter, my daughters dad married another woman, we not even an item as such but cannot go into that either. can you tell me who my next of in is? I believe it is my sister although she says it is not. I have no other living relations except 3 cousins.