Hi
I have Primary Biliary cholangitis an almost identical disease. We have been here in QLD 17 yrs now but i piggybacked on hubbys PR visa.
When we went for the medicals ,i took a letter from my specialist stating where my condition was at, what procedures i had/ required, what medication i took etc etc. I was referred ''for further investigation'' and the private specialist just did what my own specialist had done- wrote a letter listing procedures and medications and where my condition was at etc
We did use an agent , Visa Bureau, they were great but to be honest they couldn't really advise us on an individual medical condition as its ultimately up to the medical board.
Our visa was granted a couple of months later.
Good Luck with everything
Cal x