Praise be to Allah.
The marriage contract in Islam cannot be valid unless it is done by the wali (guardian) of the woman. This is usually her father or someone who acts in his stead if he is not there, such as a grandfather, brother or paternal uncle.
The marriage contract that you mentioned was devoid of this, hence it is not valid, and what must be done is to repeat the contract in the presence of the guardian if you want to marry this man.
If the guardian cannot be present, then he can appoint any Muslim man to take his place and do the marriage contract on his behalf.
It is not stipulated in Islam that the marriage contract must be done in the mosque; rather it may be done in any place, and there do not have to be any witnesses on the woman’s side, as it is sufficient to have two Muslims of good character as witnesses. But the marriage must be announced publicly, and it is not valid to have an agreement to keep it secret.
It is also not stipulated that the contract should be written down, although this is required nowadays in order to protect the rights of both spouses and to prove the marriage. But not writing it down does not affect the validity of the marriage.
The husband is obliged to give the wife the mahr (dowry) that has been agreed upon, and to spend on her maintenance enough to provide her with a place to live, clothing, and food, on a reasonable basis. If the husband does not do these things, he is falling short and is sinning according to sharee‘ah, but that does not affect the validity of the marriage contract, if it has been done in the proper manner in the first place.
We appreciate your eagerness to ensure that your relationship with this man is proper and legitimate. This is a sign of dignity and of a desire for stability, far away from the kind of relationships that Allah has forbidden.
We hope that this will lead you to find out more about the true religion which will lead to your salvation in the Hereafter, namely Islam, the religion of pure monotheism, that is based on worship of Allah alone with no partner or associate.
Worshipping Allah alone is the purpose for which Allah created all of mankind. Allah, may He be exalted, says (interpretation of the meaning):
“And I (Allah) created not the jinns and humans except they should worship Me (Alone).
I seek not any provision from them (i.e. provision for themselves or for My creatures) nor do I ask that they should feed Me (i.e. feed themselves or My creatures).
Verily, Allah is the All-Provider, Owner of Power, the Most Strong.”
And Allah knows best.