Is'my sister and me' correct

Yes, the phrase 'my sister and me' is correct for the object of a sentence or a preposition. The first persons, singular, personal pronoun 'me' is the objective form. Example:

• Mom made dresses for my sister and me.

The phrase 'my sister and me' is incorrect as the subject of a sentence or a clause. The subjective first person, singular, personal pronoun is 'I'. Example:

• My sister and I love our new dresses.