My bf wants me to move to live with his family ...?

[Monserrat]

Ok, I've been like not knowing if I'm pregnant or not because I missed my period and it's been like 3 months or so but all tests are negative but well, leaving that aside my bf believes that I'm so pregnant! but the thing is that we talked about what to do if I was really pregnant and he told me he had "a plan" (lol he is so weird sometimes), he actually told me to move to his house for 2 months until he got money for an apartment! omg...I was so surprised and scared! I mean his house is big and he has 3 free rooms in his fairly big basement, one kitchen and...well it's like a regular house it has everything and only his dad lives there in a small room and only comes home to sleep, the thing is that I don't wanna live there I kinda don't like his mother lol, and also ... I think it would disrespectful for his family, but he says that I'm also his responsability, and wants the best for me, considering my family is so going to kill me if I'm really pregnant..so what do you think? ...
Also...I'd like to add that my dad can actually beat me up...
Ok....sorry if I don't explained myself well, and yes I went to the doctor, all test came up negative but I'm gaining weight so we don't know what's happening...and also, I'm 21, and yes it is weird his dad comes back to sleep because he lives in the basement and doesn't have a home, his ex wife (my bf's mother) lives upstairs with his new husband...(10 years younger tahn her) ...
actually my question is...how can I tell him that I don't like his idea, ...or is it really a good idea? I told him my reasons but he kinda felt bad about it, but we've been together 3 years so I trust him...aaaaaaaaaaaaaa
lol...yes...We used condoms...and again I'm 21 ...lol sorry when I write I get carried way with the story so I forget to mention the important details