I'd kind of suspected this for a while, but I discovered recently -- i.e. within the past few months -- that I'm essentially incapable of holding myself to reasonable standards. They're either too low, or too high. Usually too high, but not always, and not to the same degree each time. (It's not predictable.) So, if I can't trust the standards I hold myself to, then I can't really trust myself to judge myself.
In addition to this, I've discovered that I'm so incredibly sp-deficient that I'm completely blind to my own needs, a lot of the time. So, not only can I not trust my own judgments of myself, but I can't trust my judgments regarding how I treat myself. Meaning... Unless I'm dealing with other people, or general things in the external world, I feel completely unmoored. It's bizarre, because I'm used to being certain about things, and now I'm barely certain about anything.
I presume that "this too shall pass", "it's part of growing up", "insert eye-roll-inducing cliche here". But I'm looking forward to a time when my confidence and certainty runs a little bit deeper than skin deep.