Praise be to Allah.
We congratulate you for embracing Islam and we ask Allah to make you steadfast in it and to guide your parents and your family to Islam, for He is the Most Generous.
If a woman becomes Muslim but her family do not, they do not have any guardianship or authority over her.
Ibn Qudaamah (may Allah have mercy on him) said: The kaafir does not have any guardianship over a Muslim woman under any circumstances, according to the consensus of the scholars, including Maalik, ash-Shaafa‘i, Abu ‘Ubayd and ashaab ar-ra’y. Ibn al-Mundhir said: All of the scholars from whom we acquired knowledge unanimously agreed on this.
End quote from al-Mughni, 9/377
Based on that, your father has no guardianship over you with regard to marriage and guardianship moves to the closest of your male relatives (‘usbah, i.e., male relatives on the father’s side, such as the grandfather, brother or paternal uncle). If you do not have any Muslim relatives, the director of the Islamic Centre or the imam of the mosque may give you in marriage.
If your family are not convinced about you getting married, and you fear that getting married without their permission will result in negative consequences, such as severing of family ties or a reaction from your family against Islam, the imam of the mosque or the director of the Islamic Centre may give you in marriage without your parents’ knowledge, and you can delay the consummation, waleemah and wedding party until you are able to convince them.
If you are not able to convince them within a short time and you fear for yourself if you remain without a husband, then you can go ahead with the marriage and your husband can consummate the marriage with you in accordance with shar‘i rulings, but without your parents knowing about it. Then if they find out about your relationship with your husband, you can give them the impression that he is your boyfriend and so on, because the husband is a friend of his wife, and thus you can conceal the true nature of your situation from them.
Whenever you are able to convince them, there is nothing wrong with repeating the marriage rituals in front of them superficially, so as to ward off their harm from yourself or prevent them from cutting you off.
For more information please see the answer to question no. 68752
And Allah knows best.