Just go for it. Interviewing is like any other scary thing in life: throw yourself into it enough times and it isn't. I used to be scared of jumping off a diving board, and scared of riding a bike until I did both of those things many times as well.

There's a huge salary penalty if you're not constantly looking for the best offers out there (do some Googling to convince yourself this is true). Don't worry about your imposter syndrome -- let others determine if you can get the job or not.

Elite software companies have ridiculous interviews, it's true, and you have to spend at least tens of hours practicing them. But everyone else is pretty reasonable, I've found. There are lots of enterprise shops that don't care about that nonsense.