I dreamed that my mother was giving me the good news that my cousin's daughter accepted me.

We do not have knowledge regarding the interpretation of dreams. However, if you wish to marry the girl, then examine her religiosity and character. The Shari'ah has indeed urged choosing a woman of religious commitment, as stated in the hadith: "A woman is married for four reasons: for her wealth, for her lineage, for her beauty, and for her religion. So choose the one who is religious, and you will prosper." Associating with people of religion is preferable in every matter, especially concerning a wife. You should also perform Istikhara (prayer for guidance) to entrust the matter to Allah.