Have you had a look at the beyond blue website? There's a test you can do to figure out if you have depression.
Also, there is a vitamin called wellwoman that has high levels of gla in the form of epo and starflower oil (I actually have only found it online and had it sent over from the uk) - it's not cheap, but I have really noticed a difference in mood swings since I started taking them.
You may be able to get something similar here through an naturopath?
Either way, I hope you're ok. Recognising all is not well is a good first step