Does anyone have any experience seeking accommodation at work without having a formal diagnosis? What was your experience with that like?

For context, I work in an academic library. My colleagues are lovely people. I have been here for almost a year at this point, and I think there are some changes that would greatly improve my experience.

My two issues are the reference desk and taking lunch. I am prone to getting overstimulated at the reference desk. I’ve chosen shifts at what I know are ‘low traffic times’ where I’m at a lower risk of that happening. Last semester, I had to take on extra shifts because we had an employee resign, and it was pretty rough. It is not beneficial to the library to have me on the desk when I am overstimulated. Would it be reasonable to ask that unless there is an event that leaves us understaffed (again), that I am not to exceed a certain number of shifts at the ref desk?

My second issue is lunch time. It would really benefit me if I could guarantee that I could eat without someone trying to chat me up. I don’t know how to tell people kindly ‘I would really like some quiet time to myself. I don’t mind if you are near me, or having a conversation with someone else, but I don’t want to talk right now’ and have them actually leave me alone. The only place I can guarantee I will be able to eat alone is outside, and sometimes the weather makes that unfeasible. I don’t mind if I have to leave the building and go to another. Is this an unreasonable request?