So basically, I must have as many Villages and Fields as possible?
Viewing post in Bloodbane: The Crimson Nocturne [Post-Ludum ver.] comments
Just having enough villages is sufficient (mushroom dormitories count as villages too).
That way, you’ll heal every day and won’t have any health problems. Fields are mainly there for one-time healing situations (for example, if you don’t have enough health to kill all the mobs you want in one go).
If you decide to try playing again — good luck! I hope you’ll be able to beat the game and defeat the final boss!