fussiest

/F AH1 S IY0 AH0 S T/
adjective
  1. 1

    Anxious or particular about petty details.

  2. 2

    Having a tendency to fuss, cry, or be bad-tempered/ill-tempered (especially of babies).

Source: https://en.wiktionary.org/wiki/fussiest, https://en.wiktionary.org/wiki/fussy