Congratulations (you soon to be) - doctor.
I had similar feelings when submitting my Master's Thesis. The more I read, the more I knew I needed to read more. Yet, the more I wrote, the less I needed to write, because the scope was so limited, and I wanted to explore so much more.
I have experienced, and still experience, all of this. It is crazy how much there is to read and how little we are able to write when we begin to read so much. Thank you so much for the words of encouragement!