RANT boyfriend and his mom relationship

So my boyfriend And I are expecting twin boys in a few months and I have a 6 year old little girl. We have been struggling a little since i had to quit my job because of an unexpected high risk pregnancy. We have been figuring it out on our own and haven't asked for any help. Well my boyfriends mom who does not speak English (I cannot communicate with her) and has been living in America for 23+ years. She lives about 45 mins away from us and only calls him if she needs something from him. He is just nice about it and says she is a good mom. Maybe so but for her to expect him to pay for dinner (herself and two kids from other guys). if we go out ( again only if we ask her). We don't have a lot of money $$ I even gave my boyfriend 20$ towards dinner thinking she might do the same. She doesn't care to invite us over for dinner or anything and it's been 3 years! So now she only calls him to pay her bills for her or fix her daughters computer or hers or if he could co sign for something. This time she wants him to co sign for an apartment. I'm sorry but I think she should figure it out on her own and not tie up our credit. My family isn't the best either but at least they don't ask for money or things from me . And my parents are from Europe and all learned English. Even maybe grandmother who moved her 15 years ago with heavy accent learned English. Makes me so mad. 
Thanks for reading !!!    What do you think? Am I just being prego and hormonal ?