Why and wherefore

I've been avoiding this question for a long time, but I finally have to ask it.
Why do I want a baby so badly?

I'm scared that it's the same feeling I remember hearing about when I was younger and a single friend got pregnant: "she wants something to be dependent on her so she feels worthwhile."  Or maybe it's "she has no life, but a baby will certainly keep her busy."

I feel like both of those are true.  Not completely, but they're a little bit there.  They scare me.
There are other reasons, right?  I think V and I would be incredible parents.  I want to show off the world to our baby.  I want to pour love into that baby.

Is that enough?  How tainted is my longing with the sense of worth and busy-ness?
Lesbian couples don't accidentally have kids.  It's a very planned event.  And all that planning, even though we haven't begun it, makes me question everything a thousand times over.  I feel like I need a "real" answer to the question why, and I'm not sure I have one.  Guess it's a good thing we aren't trying to conceive yet, then.