After weeks of interviewing, I just got an incredible offer to be a Junior Full Stack Developer at an amazing company. Great benefits, awesome pay, but instead of being excited I'm nervous to the point of self doubt. Can I really do this? Am I good enough to be part of this team? Did I misrepresent myself at the interview? Shit... Fucking self doubt

Look at it like this:

Either you are, or you're not
If you are, great
If not, rise to the occasion and blossom into a greater version of yourself.

Seriously though, I'm a junior dev too, and i understand how you feel, but the fact of the matter is we're all constantly learning here; your relatively empty vessel is an advantage in that you can quickly get up to speed in whatever you may have the opportunity to work with if you're not already familiar, and you're not filled with nearly as much opinions as more senior guys which will make you much more adaptable and innovative compared to the seniors who aren't willing to keep current.

If the opportunity is good as you're making it sound, just be happy and do the best that you can do, because that's really all any of us can do. Even if you spectacularly botch things, it'll be a powerful lesson that would propel you forward, and I highly doubt that you will; that's there fuckup if they somehow failed to get all the relavant checks on your competencies.

All in all, I wish you good luck, and we're all rooting for ya here.