If your doc couldn't feel them, I don't think you're feeling nods...just part of the anatomy of the neck/chin.
I was reading a post from a nurse, scolding someone who kept prodding their nodes. She said something like "first off, you think you're touching lymphnodes by looking at a picture online. In reality, it takes years of experience to know what a suspicious node feels like. Dr.'s have years of education and experience for a reason. Trust them."
If it's just a feeling, I think it's anxiety.