IB Year 2 student about to go inpatient for anorexia. Help?

Hi everyone. Basically, it's as the title says. I'm from Australia, turning 18 in a month, and suffering from anorexia nervosa (binge/purge subtype). I'm desperately trying to cling on to my course, but this disorder is consuming my life. At 5'4" and 39 kilos (86lbs), I am going inpatient on Tuesday to a private clinic. I'll be there for four weeks, meaning that I'll miss two weeks of term and my entire holiday. I want to go to Liverpool next year to study Chemistry (BSc) with honours, and I only need a 33 for it but I'm so worried that this admission will ruin my Year 12 despite my school working with me whilst I'm away. I've already missed almost three weeks of school due to a week in which I had four suicide attempts; a Valium & Oxazepam overdose, an Oxazepam overdose, drinking bleach and eating an entire box of Panadol. I'm keeping up with the content and have gotten extensions for my IAs, which I'm on track to complete. I am slightly behind schedule with my EE but that's about it. Anyway, I'm incredibly worried about whether or not my Year 12 is feasible. A teacher asked me if I could possibly sit the May exams next year instead of the November ones that I'm scheduled to sit this year. Whilst this would work with the timing of my course, I'd absolutely die of shame having to graduate the same year as my younger brother, who is doing VCE (a state certificate). So - has anyone been in this situation, or something similar? How did it work out for you? Everyone else - please share your thoughts/advice. I'm honestly ******** myself.