An ant is an insect and has nothing to do with aunt unless your Dear Aunt sits on an ant hill at a picnic!
Aunt is sort of like : Ah-nt - at least in New England!
Now, as to am'n't it is an Irish contraction of am I not and heard often there still. Sounds lovely with a soft Dublin/Kildare accent!
I use it among friends and family when feeling very Irish!
Years ago, the magazine Ireland of the Welcomes had several articles on words that came from Irish and am'n't was one of the contractions ... so I would surmise it's an Irish language contraction .... Anyone fluent?