I bet belly landed in the ocean, thats why there was no debris field. It's going to be incredibly difficult to find that plane at the bottom of the indian ocean.
Wouldn't you think if it landed in the ocean that it would have broken up or some people would have opened the doors and gotten out? The complete lack of tangible debris seems improbable.
Well it's possible that it could've landed, but it probably would've quickly sunk quite quickly after. Imagine if it landed but flipped over a couple of times killing everyone on board and breaking the wings off, then sunk. In that situation I don't think there would be much debris left floating around.