You’re correct about un-financial owners being unable to vote at a General Meeting, however attendance either in person or by proxy by just two (2) of the three (3) remaining financial owners of your Plan would be sufficient for any vote requiring a decision by a simple majority (show of hands) to be legally taken.
So the vote taken at the General Meeting to which you refer was legal, although….. as it was about the recovery of your unpaid contributions plus the prescribed rate of 10% pa interest (i.e. ≈0.8% per month on the amount then outstanding), together with the Owners Corporation’s costs of recovering its debt, no General Meeting was actually necessary as the Executive Committee or the Strata Manager if so delegated could have themselves made that decision.
What to do now?
Despite your post’s title of “bankruptcy” I’ll assume that you haven’t made that declaration, so the Owners Corporation’s legal action will likely result in a letter to you from its Lawyer or Debt Collection Agency, where your previous demonstrated efforts to pay-down your debt will no doubt work in your favour.
So when you receive that correspondence undertake to pay your next contributions installment on-time, and make an offer to repay whatever amount is then outstanding over whatever timeframe you can safely manage, and then see what happens.
I suspect that nothing will happen, because I doubt that your Owners Corporation or their Lawyer/Debt Collection Agency would bother to pursue you through the Courts for the earlier repayment of an amount of $3,700.00.
But in the event that something further is initiated, or if by some chance you have declared bankruptcy, then again speak with your solicitor or to the Australian Financial Security Authority about your overall situation.