The problem is you're just overlaying suburban lifestyle on a city without adjusting it to suit your environment. The equivalent would be a city dweller moving to the suburbs and thinking they can just walk to Walmart, when it might be 10 miles away.

If you live in a city you can just pick up milk at a convenience store as you walk by, when you need it. There will probably be one within a 5 minute walk of your house.

I would also like to know more about this milk consumption. Median consumed by US milk drinkers is 1/3rd gallon per week - your family is drinking as much milk as 36 people do every week.