Should I take an interruption I am currently in my first year of PhD at a good university, and despite everything being "in order" (my supervisor is happy with my progress, I am doing well with the teaching, a have a good life alongside my studies...) I feel that, below the surface, stuff isn't really so "in order".

For the past 3 years I have been followed by a psychiatrist and a psychologist and diagnosed with OCD, Anxiety, ADHD and Autism. These conditions led to me taking an interruption during my Master's (which I then completed with top marks) and to having "special arrangements" in my previous job before starting a PhD.

For the past months, in fact since I started my PhD, my conditions have been an ongoing issue affecting my quality of life on a daily basis. (I have difficulties developing a relation with my housemates, I barely manage to be in the office because of social anxiety, etc.) Anxiety has not improved and, in the past weeks, I feel it has been worsening and can feel I am flirting with a burn-out.

On a couple of occasions, the student advice service has advised I took an interruption. Speaking to my "advisor" (each student is assigned a staff member as advisor alongside their main supervisor), they seemed to hint at the fact it wouldn't be as big a deal as I might be making it to take an interruption.

Part of me really wants an interruption. I feel I need some time off to "catch my breath", the past years have been extremely demanding and I feel I'm not able at present to work at my best. However, part of me also feels guilty about it. I know that there are a lot of students who would like my same opportunity (academic offer, funding, etc..)

In short, I guess I'd just like some advice. Should I apply for a 3-6 month interruption?
This is a highly opinion-based question, and difficult to answer. A more suitable question might be, "what are the negative effects of interrupting and how bad are they?". My short answer: you will delay your PhD when compared to a healthy version of yourself not interrupting, but not necessarily compared to your current self continuing. So, the first thing to assess is "will it actually go quicker if I stay, or will I burn out?". The second thing to consider is how bad taking longer on a PhD is. Short answer: not that bad, many students take long, sometimes many years longer. These students still end up with post-PhD work.

Concerns over other PhD students should be cast aside, you are comparing apples to oranges. The other students are presumably psychologically healthy, they do not need a break, whereas you might need a break. The taboo surrounding psychological and similar problems means we, somewhat irrationally, treat the issues differently from other health concerns. But you should address this in the same way as any other serious health issue.