Have you actually been assessed for ADHD? If not, I would get that done ASAP to see whether you do in fact have it. It can be quite debilitating especially during university years, then you’ll have to deal with it throughout your working life. At least if you know, you can be given the right meds for it. A larger percentage of children with ADHD develop speech disorders than stuttering children without ADHD. You could have both, then with the appropriate meds (dopamine agonists), it could improve your fluency a lot. People with ADHD inherently have a much lower dopamine baseline compared to those that don’t. Your stutter is most likely triggering your severe anxiety in social situations.