When twelve baskets are mentioned we must not look for a symbolic meaning: the twelve apostles who share bread and fish receive at the end of the meal their entire travelling bag filled with bread and fish (enough for at least three days). The detail of their bags full of provisions illustrates again how Jesus did not lose sight of the goal he had in mind with the miracle of the bread (to give the Twelve a short period of rest). There was also care for later!1
43 And they took up twelve baskets full of broken pieces and of the fish.