ちっとも～ない

ちっとも with a negative means "not at all", "not one bit". It goes before a negative verb or adjective, and the sentence it sits in is usually a complaint: you expected something and none of it happened.

ちっとも needs the negative. Without it the sentence is broken, not just casual.

• × ちっとも分かる → ちっとも分からない

ちっとも, 全然 and 少しも

All three mean "not at all" with a negative. ちっとも is the most conversational and the most emotional – disappointment, irritation, a surprised denial. すこしも少しも is neutral and fits writing, and ぜんぜん全然 is the everyday all-rounder. Unlike 全然, which turns up in casual speech before a positive (ぜんぜん全然だいじょうぶ大丈夫), ちっとも stays with the negative.