I'd note that a constructive way to be self-critical is to break down the analysis into "What worked", "What kinda worked but needs improvement", and "what didn't work". Then you can focus your attention on the "almost-there" stuff, and get that figured out. As you do that, the "Didn't work" stuff usually starts becoming "Kinda worked". If you're convinced that nothing worked, go back a year or so and ask if you could have made the same shot then. Probably not - you've learned a few things since. So give yourself some credit for making the advances, and continue on.
It should be noted that sometimes you can't even ask the right question until you start picking up the right vocabulary/principles. For example, setting the aperture can seem like an arbitrary decision until you start understanding the concept of depth-of-field. Deciding what exposure method to use can be puzzling, until you start understanding the camera limits of the dynamic range. Choosing the "right" shutter speed to show motion is confusing until you start understanding how blur contributes to our perception of motion. So it is quite common to think that some photographic choices are arbitrary, until you start understanding the principles that underlie those choices.
The subjective aspects of image-making can also be hard to figure out if we don't have the vocabulary of the visual arts. For example, Andrew (Amolitor) has a nice post on colour and the colour wheel. There have been discussions of "leading lines", depth perception through use of shadow, role of texture, visual attraction to human eyes, etc. When these things are known, lots of other things start to fall into place. Without these, it is possible to produce interesting images, but hard to do so intentionally. So part of our self-critique needs to address the question of "what do we not know that we should know". This is where feedback from others helps, because others can point out something (concept, technique, principle) that you may have no awareness of. And sometimes, it is perfectly fine to say "I see your point of view, but I disagree on a subjective level".