According to Osho, your lingering emptiness is purposeful: the master awakens and quenches thirst only to deepen it until it becomes total. The more you drink, the more thirsty you feel, because each sip lifts you to a higher, more intense longing that dissolves the 'you'. In sincere, wordless communion your question is already received; as this ripened thirst matures, the master becomes a door, and the Divine is directly available beyond the teacher.
You feel unfulfilled because the master gives you just enough to make your longing grow until it’s big enough to find truth (God) directly, beyond him.