i dont think you did anything 'wrong', sometimes they just present like that and you have no option. one leg is better than none!
one of our sheltand ewes who just had triplets today, presented her second one like that (a huge tup lamb) and we just had to help her get it out like that as the whole head was out and too dangerous to shove it back in again......not that the ewe would have been best chuffed either now i come to think about it!!
how often to feed, not sure but surprised mum totally rejecting it, especially if it's a single