Leslie-
I had a patient some years ago who had lost one arm at the shoulder. She
breastfed successfully, with some trial and error work at positioning. She bf
the baby in football hold on the side with the arm, and on the other side in
a cross cradle hold, with pillows  or sling to support the head. It worked
quite well, and she also did well in side-lying position on the side without
an arm, with a pillow at her back to make her comfortable.
It's individual for each problem-but think positive!

Denise Mollenkopf, RNC, IBCLC
Florida