I used ancestry to obtain my results. I found my 1st cousins and aunt on my father's side. The process of elimination resulted that this one young lady has to be my sister but she came up my 1st cousin. There is no other men to test.
Looking at the range given for 1st cousins she is outside the perimeters.
Our shared cMs is 1170 which is outside the perimeters of 1st cousins but not quite in the perimeters of half-siblings.
1st cousin amount of cMs is between 680-1150 Halfsibling amount of cMs is between 1450-2050
What about the amounts outside the range?
Is she likely to be my sister?