Hi
I was in your position and I started my own website
www.pregnancysicknesssos.co.uk. I bought a domain name - they're pretty cheap, about £7 for two year, and then linked it to a google site. Google sites are great, you get lots of functionality for free and they're fairly easy to learn to use - there's loads of help on the net if you get stuck. I didn't have any website experience beforehand, I had a teenage neighbour help me get started and now I run it on my own. I would suggest that as the first place to start. You can keep it private while you're setting it up, then make it public once it's fit to be seen.
Then I would try and find some medics who take HG seriously. You can do this by searching research databases such as google scholar. I've just been to google scholar and put in 'hyperemesis gravidarum australia' as search terms and come up with a few papers. The authors names and workplaces are given so you can contact them from there.
Another thing is a facebook page, there's one just started in the UK
https://www.facebook.com/groups/120865887959037?ap=1.
Just in the past few months things have got rolling in the UK, mostly because of ex-sufferers getting on and doing stuff - we're fed up waiting for doctors to do anything. If you get yourself a web presence, probably other sufferers will show up and together you can move things on.
Good luck with it. If you need any help with the website, just ask.
Margaret