Hello!
Firstly, I'm very sorry to hear about your sister's passing. Condolences from MSO to yourself and your family.
I think the answer to your questions is... it depends!
JMP will use the GPA from your most recent enrolment, so they will only consider your Health Sci GPA. WSU don't make it all that clear whether they use just the recent degree or a combo of all if you've done less than 3 years FTE. It would be worth an email to WSU to see how they would calculate things. I'm also not 100% sure how GPA is calculated at JCU, again, an email to them would be useful.
You can exclude UNSW from your calculations altogether due to your ATAR, unfortunately. They continue to factor it into your application at a 50:50 ratio with your GPA and yours is too low to ever be competitive.
All that said, this is NOT something you really need to focus too greatly on. It is not something you can change beyond what you have already done (switching degree and maintaining a D/HD average), either WSU and JCU will use it or they won't, and there's nothing you can do about it. All you can do, going forward, is prepare for UCAT (note: you mentioned you've done UCAT before, but you will actually have done UMAT in 2018, so the new exam is different and you should definitely have a look at how it is administered and what the content is), and keep up your grades.
Good luck!!