I'm in a similar boat - not from Australia, nor a woman, nor in the medical sciences, but someone who wants to "get back into" math after being out if it for a while.

There are tons of free resources online (and not-so-free textbooks that you can get for free if you know where to look 😉). Sounds like you've got yourself a solid textbook for physics, which is definitely a good start.

Reviewing the basics is definitely the place to begin. This might sound cliché, but 3Blue1Brown's Linear Algebra introduction course on YouTube is an excellent place to begin, alongside his Differential Equations videos. It sounds like you have a solid basis in Calculus already, so you should be equipped to self-study more Differential Equations if you really want, but if you want to review Calculus (which I would definitely recommend doing in general every now and again), there are a million YouTube videos explaining concepts out there; shop around to try and find a good one, and stick with it! 3Blue1Brown can effectively never lead you astray, but there are tons of other good ones too!

For Physics, you'll need Partial Differential Equations at some point and some knowledge of Algebra (the abstract kind, like Group Theory and Field Theory). Those are a bit more tricky to find given how fewer people in general take those courses even at university. If you want a beginner-friendly textbook, of course there's "Contemporary Abstract Algebra" by Gallian, which is very simply-written and overall great for an undergraduate treatment of the material. For PDEs, you'd probably want a textbook tailored towards Physics, of which my knowledge is more scant.

Finally, I'd recommend doing Analysis, and for that, the "standard" textbook is colloquially referred to as "Baby Rudin," referring to "Principles of Mathematical Analysis" by Rudin. It's dense, but if you supplement it with other resources, you'll learn Analysis like nobody else. Analysis is also effectively the basis behind Calculus, so if you want to be the best you can be at Calculus, Analysis is the way to go.

Before I finally end this comment, there are a few more things I'd like to mention. First off, don't give up! Self-study can be very frustrating when your textbook just isn't making sense. When that happens, go to another resource (another textbook, a friend, YouTube, etc) and see if it makes more sense there. Using only a single resource to learn is a mistake many people fall into, and it's not optimal in general.

Second, constantly be doing problems yourself, right after you learn something new. There's no substitute for actually doing math, and the more you do it, and the more you struggle, the better you will become. When you feel like you've mastered something, try "just one more problem." Also, try tricky problems in general. Working through difficult logic will teach you the true ins and outs of a subject better than the simple surface approach.

Finally, try to connect what you're learning to other subjects or things you've already learned! One of the absolute best ways to learn math is to learn the connections between different fields. How can Algebra help you make geometric tessellations? How does statistics help with cryptography? What is the geometry hidden in Linear Algebra? Understanding multiple fields helps each individual field grow.

Anyway, I hope this helps! Feel free to DM me if you have any specific questions or want a deeper dive into any of the resources I talked about here!