I really don't get the 'essential' part of shopping.
Our 12 items would be...
Milk, Bread, Eggs, Veg, Fruit, Chicken, Meat, Soup, Bacon, Sausage, Ice Cream, Chocolate
Chocolate for all of us as a treat
Ice cream for hubby as it eases his medication side effects
All is what I would buy on a fortnightly basis, of course there would be more than one item of each, like brown and white bread, and I would buy the multi-packs say of baked beans or soups, so I wouldn't need to buy them next time.
So what are some peoples' essentials are less important to others.
Ignore your sister, get what you want.