In this context, it is problematic to define (or even outline) the terms used by exact criteria.If you are interested in the various debates surrounding the term(s) "disability" (or "illness/ disease"), there are many opportunities for independent research, online and offline. (A cursory overview of the state of discussion is currently under construction for these pages, too). Engaging with such discourses may be an important part of identity formation and personal growth.
On a day-to-day basis, finding an answer to your concrete questions and a response to the problems and challenges you face is usually even more important. If you come across a problem that is connected in some way to the topics of inclusive university education under discussion here, have a look around this website. Contact the study advisors for students with chronic health issues and disabilities. Don't hesitate to contact this specialised counselling service. Here you will find advice and support, or the study advisors will forward your request to other relevant persons within the university. The advisors offer their services on a strictly confidential basis. As a rule, you do not have to disclose any (personal) facts and circumstances to the university that you wish to keep private.
Seeking support and advice from the university early on often helps avoid an escalation of the original problem or conflict, and the range of possible solutions is usually wider if the problem is addressed at an early stage.
A chronic health issue or disability is a challenge in everyday life. It should not be a subject of shame or taboos. And you are certainly not alone with such issues at university: According to a recent survey by Deutsches Studentenwerk, about 11% of students in each year group are dealing with health impairments that affect the course of their studies.