Steenkamp campaigned actively against domestic violence and had tweeted on Twitter that she planned to join a "Black Friday" protest by wearing black in honor of a 17-year-old girl who was gang-raped and mutilated two weeks ago.
What "she stood for, and the abuse against women, unfortunately it's gone right around and I think the Lord knows that statement is more powerful now," her uncle and the family spokesman Mike Steenkamp said after her memorial.
He said the family had planned a big get-together at Christmas but that had not been possible. "But we are here today as a family and the only one who's missing is Reeva," he said, breaking down and weeping.
Pistorius was born without fibula bones and had them amputated when he was 11 months.
The man known as the Blade Runner because of his running prostheses has lost several valuable sponsorships estimated to be worth more than $1 million a year.
On Tuesday, the athlete was ousted from a pro-gay campaign being launched in Cape Town, organizers said. In a video axed from the campaign, Pistorius says "You don't have to worry. You don't have to change. Take a deep breath and remember, 'It will get better.'"