決めなくて

without deciding, not decide

→ 決める
決め decide, determine + なく Negative + て Te-form (conjunctive form)
verb · informal Rare #44,428
without deciding, not decide Negative て-form, often used with いい to say that something does not have to be done.
JA: まだ決めなくていいよ。
EN: You don't have to decide yet.
Conjugation of 決める
Past
Present
決めて決めなくて
Desiderative
Indicative present
Conditional
Indicative
Necessitative

でも今決めなくてもいいのよ

But you don't have to decide now.

— アイム・スティル・ヒア (2024)

先ず第一に名前を決めなくては。

First of all, we have to decide on a name.

どの順番で入るか決めなくていいですか?

Do we not need to decide what order to enter in?

— 親切なクムジャさん (2005)

自分のことは自分で決めなくてはいけない。

You have to make your own decisions.