Constantly feeling like you have no idea what you're doing can be a good thing.
It means you're constantly putting yourself in position to grow. It means you're challenging yourself instead of simply falling into a routine. After a while, it means you know what you're doing in a lot of areas that you wouldn't have if you'd just stuck to what you know -- so even if you don't know what you're doing in this specific way, you know what you're doing in a lot of supporting areas. Because of all the figuring out you've done in the past, you're able to figure it out this time too.
(This advice is remarkably applicable to parenting, as well.)
I know exactly what you mean. When I started in my new job (Tier 2 system admin), everyone around me was so advanced that I felt completely out of my league for months.
That feeling is beginning to abate just now, almost a year later.
It kind of sucks while you're in the grip of it - and no amount of ensuring myself "Damnit, Karunamon, you like learning, stop herping the derp" silenced that little niggling voice that says "Oh god what have I gotten myself into here, I'm so outclassed it's sad"
I'm no stranger to this feeling, however I always seem to figure it out. It's one of the traits that makes someone good a programming, there can't always be a code sample or someone there to show you how and you just have to do it anyway.
It means you're constantly putting yourself in position to grow. It means you're challenging yourself instead of simply falling into a routine. After a while, it means you know what you're doing in a lot of areas that you wouldn't have if you'd just stuck to what you know -- so even if you don't know what you're doing in this specific way, you know what you're doing in a lot of supporting areas. Because of all the figuring out you've done in the past, you're able to figure it out this time too.
(This advice is remarkably applicable to parenting, as well.)