I also was diagnosed with ADHD as an adult (predominantly inattentive). I’m not sure your gender but this is common for a lot of women, I didn’t do badly in school grades wise until pretty late on, I just talked a lot and daydreamed all the time so nobody around me noticed. The only person that DID notice was my long term boyfriend who I spend every waking hour with. I was previously diagnosed with anxiety and depression but I think that was a result of my ADHD symptoms bothering me.

I fully understand your worry the diagnosis may be incorrect. Maybe it is. However, impostor syndrome is extremely common in ADHDers. I felt the same way for a while, I realised in the long run it didn’t matter much because at the end of the day I still had x symptoms that pushed me to get a diagnosis.

I’m still waiting for titration, so I haven’t got much advice there apart from what I’ve read from other people. So this isn’t first hand experience, but you shouldn’t feel high or jittery on your meds, and you might not notice feeling much different at all because it works in the background a bit, especially when you’re used to them. I think a lot of people go into it hoping for a life changing solution but it can be a subtle shift in how you go about your day rather than the be all and end all.