YOU SAID:

I have a little sister that is five years old and might actually be a boy

INTO JAPANESE

私は 5 歳、男の子が、実際に妹があります。

BACK INTO ENGLISH

My 5-year-old, boys are actually sister.

INTO JAPANESE

私の 5 年の古い男の子は実際に妹。

BACK INTO ENGLISH

My 5-year-old boy is actually his sister.

INTO JAPANESE

私の 5 歳の少年は、実際に彼の妹です。

BACK INTO ENGLISH

My 5-year-old boy is in fact his sister.

INTO JAPANESE

私の 5 歳の少年は実際には彼の妹です。

BACK INTO ENGLISH

My 5-year-old boy is in fact his sister.