Here are there exact oil capacities for the 200tdi as specified in the Workshop Manual. One question I should ask is whether or not you thoroughly drained the sump before re-filling the oil. A seemingly daft question I know, but it's a good place to start! If the sump was fully drained, you should have been able to fit around about 6 litres into the engine and then a little more in the new oil filter. It is possible that something solid or a lump of gunge / sediment has become lodged in the sump plug, preventing a few litres from draining.