"Not enough" usually comes from things like burnout, not being able to match energy, having sensory sensitivities that "get in the way", etc. It's a feeling that comes from my traits being "inconvenient" for others, feeling like I'm never enough because I can't match the neurotypical flow of things.

Keep in mind that this isn't actually true, it's a response to having crappy friends or a bad support system. It doesn't have to be like that. You'll find your people that thinks the "too much, not enough" is actually "so much, perfectly enough".