Hi Karrebear,
I am so sorry you are feeling that way and I get upset when I see young people suffering from comparisons that should not take place, ever. Our culture is stupid and installs this program about comparing ourselves against others in our minds. We do not get anything from that.
Only comparing yourself to yourself or rating your progress with yourself is useful, and this should be to re-direct your life as needed, not to torture yourself.
And...
i wish you the best