Good luck in your new job!
Please believe me when I tell you that even if you’re in a career that may sound “prestigious”, people with ADD and/or low self-esteem still feel pain similar to what you’ve described. The low self-esteem tells us that what we do is never enough for us. If we earned a PhD, we read the research of those with a dual doctorate, like the MD/PhD, and feel grossly unqualified to publish our research. It never ends, no matter what qualifications you have!
Just love what you do and do your very best with it.