Hi Bea, I really cannot add to what has already been stated here; I think Lucyjoy stated it so clearly. The bonding process is quite individual, as I know many people who took more time to bond with their children than others (all of my points of reference are biological children of friends). Several of those who I have known that seemed to take "slightly longer" were having second children, sometimes close in age. In some cases I think mothers have tremendous varying levels of when they become overwhelmed or feel really tired; in addition, I agree that illness on the part of child or parent can lead to immobility or stress that slows down the bonding process. I know several women who gave birth and had little or no emotional/physical support from family; their processes and experiences seemed to be very different than mine. Please do not worry. Responding to the physical needs, touching, talking and keeping your baby close WILL create a bond and allay your fears. I would suggest keeping those who are creating these fears for you at bay.
I strongly suggest reading "The Baby Book" by Dr. Sears and his wife, Martha, RN. My husband and I both read it and marked lots of pages, along with many other books on parenting approaches, and found that most of "attachment parenting" was for us, and we would have used this approach, regardless of how our child came into our lives. Like 2boyz1girl, I found that some of his suggestions would not work for us, but it has been invaluable to us as parents.