Where did you learn English? Because the pronunciation of "aunt" varies depending on where you are.
It's less of a where than a who, actually. I'm from Germany, but my mom is an English teacher and her best friend at the time I went to elementary school was from London (and often lent me the English Disney VHS tapes she got for her kids, which is how I got started learning the language), both of them spoke English with British accents. My teachers at school, however, leaned more towards "generic" American English. So I grew up with a wild variety of pronunciations. That's also why my accent when I speak English is pretty noticeable, but not the stereotypical German one
(people who only heard my voice have guessed that I might be Russian or, which still puzzles me a bit, Indian).
I believe the first time I heard the word aunt was in the movie "The Rescuers" where the villain in one scene refers to herself as "auntie Medusa" and if I'm not mistaken, she actually pronounced it "awn-tee". But in every media or any conversation I've had since with English speaking people it was pronounced like the animal "ant"...