A marriage contract is considered invalid without the presence of a Waliy (a legally accountable person acting for a woman regarding marriage) and two just witnesses.
It is not permissible for a woman to conclude her own marriage contract. The Prophet (peace be upon him) said:
"There is no marriage without a Waliy and two just witnesses."
He (peace be upon him) also said:
"No woman may conclude the marriage contract of another woman, and no woman can conclude the marriage contract on behalf of her own self."
Therefore, your marriage contract is invalid. It should be renewed in the presence of her Waliy. A woman from the People of the Book is to be given in marriage in the presence of her father. If she has no father or if he refuses, then it should be done by her closest male agnate. If there are no such relatives, or they refuse to carry out this task, (Part No. 18; Page No. 181) then her marriage contract should be concluded by the Muslim judge. If there is no judge, then the head of the Islamic center in her area should do it. This is according to the evidence from the Qur'an and the Sunnah (whatever is reported from the Prophet). Moreover, a Muslim should not marry a woman from the People of the Book unless she is chaste, meaning, she is in a state of fortification against Zina (premarital sexual intercourse) by virtue of her chastity. Allah (Glorified and Exalted be He) says:
Made lawful to you this day are At-Tayyibât [all kinds of Halâl (lawful) foods, which Allâh has made lawful (meat of slaughtered eatable animals, milk products, fats, vegetables and fruits)]. The food (slaughtered cattle, eatable animals) of the people of the Scripture (Jews and Christians) is lawful to you and yours is lawful to them. (Lawful to you in marriage) are chaste women from the believers and chaste women from those who were given the Scripture (Jews and Christians) before your time when you have given their due Mahr (bridal-money given by the husband to his wife at the time of marriage), desiring chastity (i.e. taking them in legal wedlock) not committing illegal sexual intercourse, nor taking them as girl-friends. And whosoever disbelieves in Faith [i.e. in the Oneness of Allâh and in all the other Articles of Faith i.e. His (Allâh’s) Angels, His Holy Books, His Messengers, the Day of Resurrection and Al-Qadar (Divine Preordainments)], then fruitless is his work; and in the Hereafter he will be among the losers.
You should keep away from her until you renew the marriage contract. If she is pregnant, the children will be attributed to you because it is assumed that you have been married, even if the validity of the marriage contract is questionable. May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.