The other is alter-ego is the most radical and consequential transcendence in experience, but it is so only in experience. That means that everything that falls under or can be made to fall under ownness cannot stand for or be analogous in any way to consciousness in the sense of the global field of possible experience. You might even push this further and assert that what could be called the 'transcendental unity of apperception', that is the field, is utterly betrayed in being equated to that to which 'I think' can be appended, that is, the sphere of ownness. You were looking for a clue to lead you towards the originary consciousness and for various natural reasons you chose the phenomenology of 'ownness', the crystallisation around the cogito, and in doing so you simply took a wrong turn, and everything that followed from that decision only entrenched the error. Instead, look for a variant of the cogito, a sort of 'forcing extension' in which the self/other distinction is suspended without favour to either side. Which, after all has the greater weight, self or other? That's the wrong question too, both are infinite, and hence the almost inevitability of the wrong answer.