Right...Billy's measured at 500ml and that was 3 times a day. So if Meeko is on 650 2 times a day thats around 200ml worth if food less. Billy is a big boy. Rule if thumb. You should NOT be able to feel his ribs but should see the dip into his waist after his ribs end, looking from above he should resemble a pear shape.
If you decide to change try either James Wellbeloved or Wainwrights, both are good foods. The commercial ones tend to be poop x