When I discuss things with people, I rarely bounce on what they say until something hits me because I just don't know what to say. I listen to them carefully, but since I'm not answering I just give off the impression that I don't care. Because of this, it's hard to get closer to people; they just flee thinking I'm not interested.
Currently, I'm living with a roommate who talks constantly and I'm not able to have an interesting discussion with her. She keeps coming back to discussions about some facts about her or her family. It's cool because she keeps trying, but it's also painful because I've always the feelings that what she says expects an answer just to keep her interest on the subject. However, I can't find anything to say.
What I want to achieve
I don't want to appear disengaged towards people I talk to. How can I convey my interest?