Skeleton in the Closet

[GAJM1]

Just wondering if there are any experts on Autosomal DNA that could give me some advice.
My cousin and I took the Autosomal test and its shows we arent related at all (only very very far out and saying 7 to 8 generations less than 8cm's) when it should say 2 to 3 generations. This kinda confirms a family rumour does anyone know if it is possible for a 2nd cousin once removed to have as low a match as 8cm's or below? There is also a fact that my grand uncle's name is not on her grandmother's baptism or birth cert father's name is left unknown.

[MaryMc]

A second cousin once removed would share around 100 cMs with you.