The most important diagnosis I ever got was my own, and I only got that pretty recently.

When you are undiagnosed neurodivergent, you are polarising without knowing why: when I walked into the huge open-plan office of a previous job, about half the people in it decided that they absolutely did not like me without any idea of why, and a handful of people decided right there and then that I was awesome and that we were going to be friends.

I always knew I had that effect on people, even from early childhood, but I only learned in the past few years that it's because my brain runs on a different operating system than most other people's, and that people can detect that in each other instantly.

When you face a lot of rejection early on, it goes one of two ways: you either decide "please don't reject me, I'll do anything" (rejection sensitivity dysphoria, or "RSD") or "if nothing I do is good enough, then why should I bother?" (oppositional-defiant disorder, or "ODD").

Both RSD and ODD are very common to ADHD and autism (I don't know how often they're found elsewhere). RSD isn't a diagnosis, but a description of behaviours: social anxiety, people pleasing, chronic overthinking, intense emotional responses to feeling rejected - which often manifests as intense physical pain.

RSD can look a bit like mood disorders like BPD from the outside, but its causes are different: it's a form of compound post-traumatic stress disorder from e.g. years of being bullied, and that person needs talk therapy, not lithium.

So that's why it's really important to get the right diagnosis, so you get the treatment that you need and not the treatment that you don't need.

If you're constantly on edge, trying to explain other people's behaviours that you don't understand, and (most importantly) misreading social cues and having to learn about them from books, that suggests that maybe there might be something else going on here.

All the best with finding your answers, however you find them.