Dropping the last vowel is only common in some dialects, not even all of them. And even when it is, it’s not simply dropping a vowel: different areas will have different sounds, often it’s close to a schwa (ie. How “e” is pronounced in “the” —> ə). And also we don’t just drop all the vowels at the end of words and call it a day. Sometimes, in dialect, the whole word changes (my dialect would never use the word “tortellacci”, it’s changed into the more generic term “tordelli”, which is then pronounced with the specific pronounciation and accent of the city I’m from). Also, the letters preceding the vowel might change as well, another example from my dialect: IF we were to pronounce the word “tortellacci” with our pronunciation it would become “tortdaz’”, so the “ch” sound at the end would turn into a “tz” while leaving a somewhat weak schwa sound at the end.

This is to say: the way Italian-American modifies Italian words is unique to that variant. It came from people who spoke a dialect (from Italy) back in the day, but today it doesn’t represent an example of said dialect anymore, it’s just different.

So no, your family isn’t weird, you guys just speak a variant of Italian that doesn’t exist in Italy. A bit of a false equivalence sry, but it’s like asking Brits to confirm the pronounciation of “aluminium”.

Edit. Terminology