Is my marriage to an orphaned girl whose father has passed away and who has no male siblings valid, given that the marriage contract was concluded in the presence of both families and with the testimony of her two sisters' husbands, and without the marriage notary asking for explicit consent?

The aforementioned contract is incomplete and must be renewed for two reasons: First, the absence of a guardian for the girl. Guardians are not limited to the father and brothers; they also include the grandfather and paternal uncles. If the guardianship of the closest one falls away, the next in line marries her off. If the guardianship of all of them falls away, then the ruler is the guardian, as the Prophet, peace and blessings be upon him, said: "The ruler is the guardian of one who has no guardian." Second, the absence of uttering the formula of offer and acceptance without an excuse. Writing alone is not sufficient, as the guardian must say: "I marry her to you" or "I give her to you in marriage," and the husband must say: "I marry her," "I accept her in marriage," or "I accept her marriage."