The “informal” approach is entirely understandable given the previous situation but there are legal obligations for you to have an AGM.
At the very least, the new strata laws require you to review your by-laws before November 30.
Also, Section 18 of the Act also requires you to hold an AGM withing the financial year. Since the building hasn’t had one in the past 12 months, then you should have one before June 30.
Obviously, there’s no need to get too formal or bureaucratic about all this – but it’s important for the resale value of your (and their) property that things are seen to be done properly and there is a record of meetings and decisions like insurances, for instance.
One thing to be wary of in self-managed schemes is the “let’s just divide the bills equally” scenario. Your liabilities, such as levies, are based on your unit entitlements and you should not waver from that.
Download a copy of the Act here and look at Schedule 1, Part 2 for all the things that need to be on the agenda of your AGM. But don’t get all “bush-lawyer” about this. It’s better to be on good terms with the majority owner than be pedantically correct on every detail.