My father committed suicide in 1985 when I was 16. My mother passed away February 10th, 2011 after a stroke as I held her hand in Hospice. After grieving for 25+ years over the tragic death of my Father I thought I was equipped to handle anything. I found out I am not. This seems to be getting harder and not easier. My sister and I just finished cleaning out her apartment last Friday. Maybe it's because I have been so busy with the details of finalizing everything after her death that I really never processed it? Someone told me in Hospice that she felt like an orphan after both her parents passed away. I laughed at the time. I totally understand now. I am married with 2 kids, extended family and friends and neighbors who all care about me but somehow I feel totally alone. Like I lost everything.
What you are feeling is very common. We all mourn in different ways, in fact, it annoys me when someone expects you to bawl your eyes out and throw yourself to the ground at funerals. I tend to internalize and try to figure out things over time. It doesn't mean that you loved someone any less.
Also, as time goes on, we feel our own mortality and try to relate that to our experiences with loved ones who have passed.
As long as your bereavement doesn't inhibit your day to day life and relationships, just take it one day at a time.
I happened upon an unusual website that you may find interesting. It has stories of how people cope with the loss of a loved one through art and sharing experiences called that daily undertaker.
It sometimes helps to know that others are going through this. I try to imagine live without my Mom who I have known for over 50 years and I can't wrap my head around it.
good luck