YOU SAID:
It's my birthday today. I want cake.
INTO JAPANESE
今日は私の誕生日です。ケーキが欲しいです。
BACK INTO ENGLISH
Today is my birthday. I want a cake.
INTO JAPANESE
今日は私の誕生日です。私はケーキが欲しい。
BACK INTO ENGLISH
Today is my birthday. I want a cake.
That didn't even make that much sense in English.