It takes a not insignificant acreage to feed a household. It will vary a bit by soil quality, farming techniques, and what crops they are growing. And then you need to factor in the other things such as crop rotation/leaving fields fallow. And plots for other things (because you're not just eating a single crop). You can find tons of data for all of this online and it can be fun to read about it. So if anything, those fields are too small lol.

As for the map, it's good, I really like it.