Dealing with PPD.

I had my first baby 2 months ago and I still find myself struggling with depression. I talked with my OB who gave me Zoloft which has been helping for the most part. Sometimes I just feel like a horrible mother because people ask me if I could even imagine my life without her, and the honest answer is that I could. Don't get me wrong, I LOVE my daughter but I don't feel the overwhelming love that most moms describe. I'm just kind of numb and going through the motions right now. Has anyone else felt this way or is it just me?