Perhaps I am missing something, but wouldn’t the waterproofing of a previously unrenovated bathroom in NSW normally be the OC’s responsibility?
I would make absolutely sure about that before going further. I assume your Strata Manager thinks it would be your responsibility, so you may have to go further and consult a lawyer. The NSW Dept of Fairtrading Strata section can give advice on responsibility for repairs too, (although I think some on this site have found it unreliable). Peoples opinions from this discussion will give you a clue as well. Then go back to the Strata Manager with your advice.
NSW Strata Law defines what is a major renovation, so the need for the by-law and vote at a General Meeting is right, but only if you are doing a bathroom renovation and/or involving waterproofing. Part of the point of a by-law is to transfer the future responsibility for the work to the owner. If it is the OC’s responsibility to repair (even if repairing the waterproofing is a major event) then one wont be needed.
However, given the disruptions involved in such work, you may find that doing a renovation at the same time is the most sensible course (or paying extra to get the materials used by the repairer to be the ones you choose) in which case I am not sure what is required. Anyone?
Someone else may be able to say whether EGMs can now be held by electronic means instead, in which case calling an extra meeting may be even easier and cheaper to do. But as already said by others you definitely don’t need to wait for the AGM in November.