I have a real problem with the method of self-inquiry as promulgated by Robert Adams, and often by Ramana, and that is you can get lost; lost in the perceived emptiness of the Subtle Body, or in the comfort of knowing nothing in the Causal Body where there is no self-awareness, only awareness.
Practicing This way, asking "Who and I?" and waiting for an answer, or following the I-thought to where it appears or disappears is much like practicing a Mantra. It is only to empty the mind, and Self-Realization of the Jnana sort can arise from an empty mind alone, it can also arise in other ways.
The problem with following the I-thought is that it arises from one's perceived emptiness and disappears into emptiness. A few years of doing this and you will identify with emptiness and become a shell with no emotions and no motivation for life. This can gradually give way to identification with the witness of emptiness, or the Absolute. You become a pure passenger watching the phenomena of your life pass by. Such is how Nisargadatta described his current state in his last book, "Consciousness and the Absolute."
But I ask, is this what you want? Peace, rest? Or would you rather know yourself as Consciousness and the energy, drive and force of Consciousness, the Shakti?
Would you rather know yourself as love, bliss, and embodied energy acting out thee will of God, or as Nothingness?
Would you rather be an observer or a 100% participant in life?
This is the difference between the Bhakta and the Jnani or Sage.
The way of the Bhakta is filled with sound and fury, divine love followed by deep despair, followed by being wracked first by deep bliss often felt as orgasmic, with a high sexual tension, and then followed by physical pain of a tensed body, unfulfilled desires, and a deep longing for both fulfillment and rest at the same time?
The way of unity with Consciousness is obtained through love and surrender to another, whether God, Guru, Lover or other, whether their path is pure Bhakti, or awakening the Kundalini or Shakti. It is dualistic.