[wpietri]

I agree with others that maybe you should consider whether working at a fancy company is really the only thing you'd be happy with. That goal strikes me as motivated by social status, not the work itself. I don't think that's a sustainable motivation for a software career.

But I mainly wanted to address the anxiety. Programmers definitely skew anxious; it's a trait that's in many ways beneficial. However, it's easy to let it run away with you. I have been coding since I was 12, and I still regularly have feelings that I'm too dumb to tackle whatever it is that I'm working on. I'm not; I just get uncomfortable when I'm not sure what to do next.

The main way to get past that is by accepting that you have particular feelings in particular circumstances. There's a difference between having a feeling and believing a feeling. If you are having trouble finding that difference on your own, find a good therapist (you may have to go through a few) and work on it with them. At your age I would have tried to macho my way through those feelings, but now I look at that as yet another way I let my reactions drag me around by the nose.

Good luck sorting this out! And thanks for asking such a good question. You've helped way more people than yourself with it.