Is it permissible for a son to marry his paternal aunt's daughter after his stepmother breastfed him two or three times when he was a child?

Prohibitive suckling occurs with five satisfying sucklings within the first two years of life. If this is established by the testimony of one woman, then the young man becomes a mahram to the mentioned girl, and she becomes his sister's daughter through suckling, and it is unlawful for him to marry her. However, if the suckling is not established, then he is permitted to marry her.