YOU SAID:

I came in to the room with your mother

INTO JAPANESE

お母さんと一緒に部屋に入ってきました

BACK INTO ENGLISH

I came into the room with my mother.

INTO JAPANESE

私は母と一緒に部屋に入ってきました。

BACK INTO ENGLISH

I entered the room with my mother.

INTO JAPANESE

私は母と一緒に部屋に入りました。

BACK INTO ENGLISH

I entered the room with my mother.