Hi neutrino, is there a chance that if you don't accomplish some of the things you "want and need to" accomplish you can take another shot at them at another time? If so for those tasks how can you have failed?? You just haven't got there yet, that's all!! They're still there, they're still there to accomplish, when you're ready.
As for other things then maybe have a think about whether they're really worth putting your whole sense of value on. I'd say someone's real value can often be far more than than a handful of accomplishments.
Although having said that I get the feeling that you're underestimating your true achievements, your true qualities. And even things that seem relatively "minor" that you are/do/say can mean so much to someone else or can signify real purpose in your life if you give yourself the opportunity to see that.
But you're looking to be something more?? well it's OK to have (realistic) goals but why should that have to dismiss the "Even though I'm quite happy with who I am, my interests and my personality"?? I'd say you should really hold onto that, sure add bits you feel comfortable/happy with along the way but just don't lose that bit.
The most important thing is that you can feel comfortable/happy with who you are. Doesn't matter about "should"'s, "should have done"'s so much it's who you are that really matters.
Although I think you're right in that the depression/anxiety may be distorting things for you. And not only distorting things but "putting the brakes on" a bit, on you achieving all you could.
Are you getting any help with this?? Are you getting enough help with this?? Maybe it's worth trying to separate it a bit from YOU?? And try to remember/remind yourself that you ARE good enough!!!
Here if you want to talk about it some more................
Alison