I understand that お腹が空きました means "I am hungry" since its literal translation would be "My stomach has become empty". Meanwhile, お腹が空きます is closer to "I get hungry" as in よくお腹がすきます. So far things are clear.
However I'm confused about negating the sentence to mean "I am not hungry". The books says it's either (...)空いていません or 空きません. I'm fine with 空いていません, but shouldn't 空きません be 空きませんでした instead? What's more confusing is お腹が空きませんでした means "I was not hungry" while I thought it should be "I am not hungry" since it negates お腹が空きました.
Could you please clarify my confusion?