手を付けずダラダラしているくせに、「うへー、今度こそ間に合わないかも！？」と心はビクビクしている。

、「、！？」。

Even though you're slacking off and not even touching it, your heart is anxiously whimpering 'ugh, maybe this time I really won't make the deadline?!'

Literal

Hand [obj-を] don't-attach-[without-ずに] sluggishly doing [despite-くせに], 'ugh-, this-time [emphatic-こそ] in-time don't-come-up [maybe-かも]!?' [quotative-と] heart [topic-は] is-anxious-trembling.

A rich portrait of procrastination psychology. 手を付けず ('without touching it') uses the formal ずに for 'without doing X.' ダラダラ is the mimetic for lazy, sluggish, drawn-out behavior. くせに ('despite') adds the contemptuous 'and yet.' 今度こそ ('this time for sure / this very time') — こそ gives exclusive emphasis. 間に合わない ('to not make it in time') with ~かも ('might') for hedged panic. ビクビク is the mimetic for nervous trembling. The whole sentence contrasts outward sloth with inward panic beautifully.