This Could be Heaven

A global pandemic left only 20% of humanity surviving.
A zombie apocalypse left 15% of those left alive living.
A nuclear explosion left 10% of the remaining humans alive.
A huge earthquake left 5% of the remaining people living.
Roughly 11,550,000 people remain in little pockets around the globe, surrounded by harsh forests and mountains.
Heaven Fridman is one of the few new children born after the devastating events. This all happened over a span of 90 years, and her Grandmother, Granny Harriet, was only 7 when the pandemic broke out. A mere 8 years since the earthquake, humanity is struggling to move on. Heaven happens to play a major part in the rebuilding.