Marcia Mitchell, the mentally troubled mother of two who tried to smother her infant daughter in a Buffalo hospital, was sentenced Thursday to 3 1/2 years in prison.

Mitchell insisted that the woman who attacked “my beautiful baby girl wasn’t me” and told the judge she had spent her 659 days in jail in Buffalo “trying to figure out what went wrong” when she tried to kill her infant daughter, Kelie.

State Supreme Court Justice Penny M. Wolfgang imposed the prison term on Mitchell’s plea to attempted first-degree assault for the incident May 30, 2008, in Women & Children’s Hospital. Kelie was 7 months old at the time.

“I realize I made a horrible mistake. I miss my children exponentially,” Mitchell told the judge.

Mitchell, 29, said that at the time of her crime, she was “under extreme stress,” with both of her daughters hospitalized. She said she got no help from family members after her Batavia flat was destroyed in an April 2008 fire.

Wolfgang imposed the minimum prison term possible. She also imposed an order of protection barring Mitchell from contacting Kelie before Nov. 30, 2019, unless she gets the approval of the court and mental health experts.

Defense lawyer Barry S. Dolgoff told the judge that Buffalo psychologist Charles Ewing has diagnosed Mitchell as suffering from a syndrome that makes an individual prone to exaggerating or fabricating problems with a child and possibly hurting a child to call attention to herself.

Rosanne E. Johnson, chief of the Erie County district attorney’s Special Victims Bureau, told the judge that psychiatrist Gary Horwitz recently examined Mitchell for prosecutors and determined that she had consciously intended to harm her child.