I think it is in the combination of food that can make you feel hungry even at 2600 cals. I don't know how your diet is like but if your basing most proteins or carbs in shakes that can be a point... other is that some carbs can cause you to feel hungry due to insulin sensitivity so check well the times of the day that you are eating each one.
On the other hand... the ratios are of influence too... if you are high on protein and little carbs, protein cals are absorbed and used faster than other nutrients...
hope this helps.