He isnt legal and bought up marriage

Okay I have been with my SO for 2 years. I'm currently 33 can weeks pregnant with his first baby and my second. Anywho, unfortunately he isn't legal here and is an immigrant. Now the other day marriage was bought up. When I first got with him I made it known I never ever want to be married. It's not my cup of tea and I just never wanted it. Not sure of my reasons why but yeah. So his exact words were "why don't you just marry me at a court house so you can help me get my papers and we can live a better life" cause no lie right now his job sucks we barely make rent and afford the babies.. he is limited on his work and everything else but when he said it along with papers it made me feel like he only wants it for the papers. But he is sort of right in the situation like we can't buy a house together he can't get his own car he hates driving just in case anything happens. Idk.. what would you ladies do? He stated to my mom when she asked about it that he doesn't want me to believe that it's only for the papers but why didn't he just do a proposal than bring it up with the papers ugh. We been fighting quite a bit for the simple fact of money issues I lost my job due to high risk and his job literally sucks. I drive him around smh idk guys im in a mental mess and confused. I don't want to be used and just never wanted to be married but I also don't want to buy things alone and things be hard because of my only income. ****And let me just say this baby wasn't planned I was on birth control and still got pregnant and I'm not the type to terminate or anything*** with that being said he also knew I didn't want marriage when he stayed in a relationship with me.