All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
What both of you did is not correct at all because the method in which you conducted the marriage is not Islamically valid as the Prophet said: “Any woman who gets married without the consent of her guardian, her marriage is void (and he repeated this thrice).” [Ahmad]
The Prophet also said: “No marriage can take place without the presence of a guardian and two trustworthy witnesses; any marriage that was not conducted in this manner is void and the Muslim ruler is the guardian of any one who does not have a guardian”. [Al-Haakim]
Indeed, Islam has emphasized the conditions of legal marriage in order to protect the rights of the woman as well as the rights of the children she gives birth to. If the marriage were to be done in the way you did it, any man who does not fear Allah may deceive any woman and agree with her in the same manner that you did and then he enjoys her but when the woman gets pregnant, he leaves her and denies having any relation with her or with the fetus in her womb, so her rights and the rights of her fetus will be lost.
However, if the marriage is conducted in the presence of the woman's guardian and of the witnesses, and the marriage was made public and was documented, then the husband can not escape the rights that are incumbent on him by marriage.
You should also know that it is forbidden for you to know a man in this manner or to love him. Even if this happens, what you should have done is that as soon as you got to know that man and you were pleased with him as a husband, you should have told your parents and informed them and tried to convince them that he is suitable to be a good husband for you. If they agree, then this is what is required and the marriage should be then conducted in an Islamic way. But if they refuse without having a sound reason, and you insist to marry him, you may take your case a Muslim judge in your country. If there is no Muslim judge there, then to the Muslim community who may act on his behalf.
Now, both of you should sincerely repent to Allah. Also, you should keep away from that man and never let him touch you [i.e. have sexual intercourse with you], as this is one of the conditions of true repentance. That is because having sexual intercourse with that man is pure Zina (fornication and adultery) which is forbidden. Then, if he wants to marry you and it becomes evident that he has really repented to Allah, he should then wait until you have at least one menstruation period to make sure that you have not got pregnant from him due to him having sexual intercourse with you before, which you come to know now that it was pure Zina. After you have your menses and it becomes clear that you are not pregnant, he then may conduct the marriage contract in an Islamic way as clarified earlier.
However, if you have become pregnant from the sexual intercourse you had with him before, then he should wait until you give birth and then he gets married to you in an Islamic way as to avoid mixing the semen of Zina and the semen of legal marriage.
Besides, if a child is born from the first relation [before the legal marriage], then the child should not be traced back to that man even if he was his true biological father because Islam does not allow adoption.
Since, there is no legal fatherhood, so what does not exist legally is like it does not exist in reality.
Allah knows best.