Teacher and student: listener question

Hi Clare, I am a listener of your podcast and I have a question I've been wrestling with for awhile that I'm hoping you can touch on. I am struggling with the teacher-student aspect of this understanding or any spiritual understanding for that matter. In my life, I feel like I constantly have so many questions about what is true or not, who is telling the truth and really just what is the truth? And listening to non-dual teachers, reading books, watching videos or anything is relieving a bit because it feels like I am getting an answer. But that feeling never lasts for very long and often I question the teacher themselves. I'm wondering if full understanding of truth is only possible through the self, with no external input. Is it necessary to come to the truth on my own. 
 I realize this is rather ironic that I am asking you, a teacher. However, I'm not sure what else to do.