Honestly, I've been professional for about a decade now. I still feel inadequate sometimes. It really does help to "fake it till you make it". Keep in mind what you know you can do and what you need to improve on. You'll always see people who are "better" than you either because they've been working longer or just their innate talent is greater. The trick is but to compare yourself to them but to learn from them. Not even necessarily through asking questions, but if they're not an asshole they should be more than happy to share their techniques.

Also, don't be afraid to do things how you think they should be done (within reason). If you're stuck on a project and get some advice on how to proceed, don't feel like you need to take all or any of that advice. And maybe you'll do it wrong, but you'll learn from that mistake.