Might be a tad stuck

I was under pediatric rheumatology until last April due to chronic pain which (among a few other health issues) meant that I have access arrangements (extra time and rest breaks) in exams. I had a difficult enough time getting my college to give me these despite having the evidence, but that's not what this is about XD I'm applying to university in the next few months and if I do end up going, then I will need to apply for my access arrangements through the university, however I will probably need a letter (minimum) from my doctor, likely my rheumatologist as my GP is awkward, is very inconsistent, didn't diagnose me, and is almost impossible to see. The only issue is, I can't remember whether I had 3, 6, or 9 months to make an appointment with my rheumatologist before I'm completely discharged and would have to go through my GP and adult services if I needed another appointment (which would probably take several years). I really hope it's 9 months, because if it isn't, I'm stuck, and even if it is, I'll have to sort everything out almost as soon as I send in my uni application