All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His Slave and Messenger.
There are certain conditions for the validity of a marriage contract. Among the most important of these conditions are the (consent of the bride's) Wali (legal guardian) and witnesses. Please refer to Fatwa 83629 about the conditions for the validity of a marriage contract.
If this marriage was conducted without the consent of your Wali, then it is considered invalid. The scholars held different opinions regarding whether such a marriage is to be declared Faasid (defective). The jurists maintained that a marriage annulment or divorce is necessary in such a case. Ibn Qudaamah said: "In case of a Faasid (defective) marriage, it is impermissible for the woman to marry another man unless he (the man who defectively married her) divorces her or the marriage contract is annulled. If the husband refuses to divorce her, the authority has the right to issue a marriage annulment as stated by Imaam Ahmad." [Al-Mughni]
Some scholars, on the other hand, held that there is no need for a marriage annulment or divorce; however, the first opinion is stronger. You are advised to refer the case to the parties concerned with the settlement of Muslims' affairs, such as Islamic Centers. Please refer to Fataawa 125598and 143529.
Finally, we would like to highlight two important points:
First, stating a fixed amount of Mahr (bridal gift) is not among the conditions for the validity of the marriage contract. Please, refer to Fatwa 85388.
Second, maintenance dues become obligatory when the wife hands herself over to her husband, physically or effectively, by the woman being there for her husband when he wants to sleep with her. At that point, it is incumbent on him to provide her maintenance needs.
Allaah Knows best