Well, I suppose that's a harder question to answer. In some sense, I think you're being hard on yourself: I would find it really unlikely they would have any conversation with you at all if they didn't want to. And frankly, you give me the impression of a nice guy, and I think most people like to chat. So, just... assume they do want to talk to you. Like I said in my latter post, if they're never asking about you and the relationship is onesided, then there are other problems and you may well want to follow Tress' advice. But if this is just a small-talk complaint, or an occasional problem with some friends, I would guess they're just a little self-centred: in fact, they even do want to talk to you, just... about... themselves.How am I supposed to do that if I'm not sure they really want to be talking to me?
Lately (by which I mean the last year or so) I've become a lot more sociable, and I find that just assuming people want to talk has done wonders. Not only have I gotten a LOT better at social interaction, I've made friends and discovered that some people really just need someone who listens, because they get stuck in a lot of those 'one-way, people never ask me about me' relationships.
You're doing the right thing by asking them how they are, and I don't mean to downplay that, by the by. I've definitely been where you are, including the insecurity about whether they even want me around.