Right! If it's body you're after, add malto-dextrine. That will add body. Not too much, though! (my son made root beer jello-o after misreading the amount of malto-dextrine to add).
If you want sweetness, the lactose would work great. It's a non-fermentable sweetner used to sweeten stouts (that's the "milk" part of a milk stout- lactose is actually milk sugar).