A “casting” vote is an additional vote given to the chair (or NOT, in this case) when a vote is tied (and only when a vote is tied).
A normal vote by the chair is not a casting vote, even if it tips the balance one way or the other.
I strongly suggest that at your next AGM you either lose a seat or gain one. Even numbers lead to all sorts of unfortunate things like … um … compromises.
But seriously, ask any strata manager and they'll tell you even numbers on ECs are a nightmare.