Welcome to the forum! You're in the right place to get support and advice :)
I'm sorry to hear you've lived with depression for so long. A number of others on this site have also experienced long-term depression. I've had OCD (an anxiety condition) for almost a decade now. I was diagnosed when I was 13. Do you regularly see your GP about your depression, or have you in the past? Also, have you tried seeing counsellors or psychologists? There's a good chance you have, but perhaps you didn't feel that you found the right professional - someone you can relate to. If you would like to see someone new about your depression, there is a directory on this site for accessing professional services in each Australian state. Go to the first option in the top blue menu (Get Support) and select Find a professional.
Having social support is vital for anyone, and especially for those with a mental illness. Try to spend time with family and friends as much as you are able to. I know that I would not be as happy and healthy as I am now without my family, my best friend, and new friends I've met recently.
Hopefully other people with more experience of living with depression will give you some advice too :)