Poop very little after large meals?

Eat more veggies. Your body is an amazing digestion machine. If you are eating mostly meat and carbs, there is not going to be much leftover! poop is made up of mostly fiber residue (roughage), bacteria, GI secretions and water. I suspect you are not eating enough fruits and vegetables to give bulk to your stool. I recommend 25-30 grams of fiber per day.