Design Confidence
Designers are a self-critical bunch. It's in our nature to critique and we are our own harshest critics. I see it all the time; myself, my friends on Twitter, the people I hold in high regard. It's a normal aspect of a creative field.
Don't worry! It's normal. It happens, and it will pass. Grab a cup of tea, read a book, go for a walk, put some new music on and relax. Let the storm pass and get back to it. No one expects you to be the best damned web designer this world has to offer, and no one will tell you off if you aren't.
Confidence can be a real problem for designers. Nearly all our work, or the end result of our work is balls-out in the public realm for everyone to see. Every mistake, or not-quite-perfect element is there.
You have to accept you win some, and you lose some and doing your best is all you can do. If I feel I've not done my best work, I often add a few extra hours of my time if I feel I'm not at my best for clients so that I can do my best work when I'm feeling better. I'll go away and focus on something else and come back refreshed.
Even with Project Managers and Creative Directors you are the number one person responsible for your output. Remember, design is about goals, not how many widgets you create or hours you put in. It's about getting the best results for the client or project.
I've not met a designer I've loved who wasn't incredibly humble; people of all varieties and skills. We constantly seek the white whale of perfection and we grow daily. If you're not looking at designs from 4 months ago and saying "Oh, I could have done this better" then I would be really surprised. Since I started designing it's been that way for me constantly and has shown no signs of letting up.
I've been wanting to write this for a while to remind my friends to remember that they are good enough! You're good enough that you're standing where you are and you're doing what you love. Good luck!