What do I do...my girlfriends mom thinks i'ma loser?

I'll make this short. First and for mor you have to understand that me and her are both 20 yrs old! She is NOT allowed to see me because she lives at home with her parents. She wants her parents aproval so bad...thats why she hasn't moved out with me. I confronted them in walmart...i asked her mom why she hated me so much. She told me it was because i was a loser. I mean come on this isn't high school anymore. So what am i supposed to do? How do i get her respect? She doesn't even know me!