日本語能力試験を受けたい

日本語能力試験をうけたいけれど、１２月にうけたいか６月にうけたいか分かりません。

I want to take the JLPT but I'm not sure if I want to take it in December or June.

I would say: 日本語能力試験をうけたいです。でま12月にうけようか6月にしようか、きめていません。

(literal translation would be: I want to take the JLPT but I haven't desided wether I take it in December or I do it in June.)

Goog job! I hope this was helpful. Good luck!