I know Rookie Mag is an online mag for teenage girls but let's be honest here - how many of us feel like a fully fledged adult - like ever? And the issues that effected you as a teen or pre-teen still rear their head every now and then - well far more often than we like. You then beat yourself up for not being more together, and being a strong confident woman. Well being a strong confident woman is a bit about being a strong confident woman, a bit about knowing your demons and not to be afraid to keep addressing those demons until they become more friendly and it's also a little about faking it. The most confident person in the world will still have moments where they feel a wreck and don't you believe the media when they try to tell you otherwise. In fact, whilst we are on that subject - maybe don't believe the media on most things!!!
But here's a great article about How to not care what other people think of you - it's mostly aimed at teenagers but I bet you can still find something you relate to in it.