I think she is still having mixed feelings about her loyalty to her family and is getting pulled back there. I am thinking as her parents get older and really are getting feeble, she might insist on looking after them all the time. I recall that traditional marriage vows say "forsaking all others." I think you should be first in her life at this point. It concerns me that she takes their side, and you get ignored when you are with them.

I don't intend to cause you any hurt, but it could be that you came along when she was annoyed with her parents, and she saw you as a way to escape them. Now she is not annoyed, so she wants to be with them more.

Have you considered asking her about getting marriage counseling? It would be nice to give it one more chance.

However, I do think if things don't change, then you will be more and more miserable. She can't seem to really commit to you and to the idea of being married. That's my opinion, anyway.