Baby Bond?

My son was in NICU for about 6 weeks. I visited him there everyday and I am so happy he's here and doing well. The baby is home now, and I find myself not feeling very connected to baby. I'm just exhausted with baby care, part time job, keeping up house, doing chores and errands. Taking care of my son just feels like another thing to do, which I know that sounds awful. I felt more like a mom when my son was in NICU. Now that he's home, those maternal feelings seem gone.

Why am I feeling this way? Why can't I seem to bond with baby?