I hear you. I didn't feel connected or excited until about 22 or 23 weeks. For me, the pregnancy was unplanned. Regardless of whether it's planned or not, though, I don't think you should feel guilty for having mixed emotions. There is a reason we are pregnant for nine -- or 10 -- months. I think emotionally connecting with the idea of your baby and the life changes that come with it is a process. For some women, maybe it's a short one. For some, much longer. I think those differences are normal, and I think it's healthy to let yourself experience those mixed emotions on your own time schedule.
I write a blog called Unexpectedly Expecting where I've covered a lot of this stuff... you can read it here: http://stalicious.typepad.com.