I have only had an early loss at 8.5 weeks, but have had stressful pregnancies where they find problems with my babies. I felt very detached from my DD while pregnant but then bonded once she was born. With this pregnancy, I feel distant too, We just had a scan today to check out a possible problem with his kidneys and all looks good at the moment, though I still find myself feeling a bit detached. I think when you have experienced loss and/or complications it can take the joy away even though you want to feel good about it as walls are put up to protect ourselves.
Best wishes for your current pregnancy