I believe that award availability for Qantas Frequent Flyer SIlver members only open till 297 days from today. So that means there would only be availability for you up until November 12. You might have to wait a bit to see the full picture of the award availability for your routes.
A bit of planning help. You might want to consider going through North America on one or both ways of your journey. That can help with your award availability woes. Qantas only flies to one destination in South America, that being Santiago Chile. I believe for now you can still redeem your points for travel on LATAM airlines but I’m not sure how long it’ll last as they are leaving oneworld this year.
Bronze and silver members should see the same availability at the same time. Good luck.
Be flexible with dates and cities you fly from/via (cities within AU) (cities via Fiji, HKG, TYO). Will/may costs more pts but at least they may be more availabilities. Check all Qantas flights (from multiple AU cities to USA cities.