Half sister

I am ISO my half sister whose name is possibly Deanna Marie (Pomroy, Reitan or Fraser) who was possbily adopted with in the family in the fifties or early sixties at the latest. We share the same mother, Cynthia Jane Pomroy and the father is possibly Robert (Bob) Roth, both of the Twin Cities area. Mother was about 16 when Deanna was born May 10th (1954 to 56) but was not given up for adoption immediately. We're of Norwegian heritage mostly so the possiblility of fair hair and eyes are great but not limited to. I am the youngest being born in 1977 so the age gap is by some years. Any help would be appreciated. I am stationed overseas in Italy so it's hard for me to order those search agency things for the lack of being local. Thanks!!!! :)