My mum died from advanced breast cancer in April 2004. She was first diagnosed in 1999.
Sadly, although she had passed her 5 year survival and had been given the 'all clear', she had been diagnosed with secondary bone and liver cancer. She died after her first session of chemotherapy as she contracted an infection, which killed her within a week.
Her death was a shock, in that we had thought that she would have at least a year or so - but we knew that her prognosis was not good.
At the time of her death I cried, and I shed some tears over the next few days.
However, apart from that, I felt that I was not grieving 'properly' - i.e. I always thought I would be totally devastated, hysterical, tearful, etc.
I was very close to my mum.
Eventually I went to my GP because I really didn't know what was going on. I was referred to a counsellor, who talked to me about my feelings. Ultimately she said that it sounded like I had been 'steeling' myself to deal with my mum's death over the years since her diagnosis.
Also, we had a very good relationship, so there was no 'unfinished business' and no regrets (beyond the obvious).
It made me realise that I was actually seeking someone to give me permission to feel the way that I did, and to allow myself to be as I was - and that just because I was not falling apart/lying prostrate with grief on the sofa didn't mean that I was a bad person.
Almost 5 years later, things haven't changed for me. I was fearful that I would have a mental collapse some years later, but this hasn't proved to be the case. I remember and think of my mum every day, and no longer worry that I am suddenly going to fall apart. (I do worry, though, that when my dad dies, things might change).
So this is a very long and rambling way to say to you that you should just allow things to pan out on a day by day basis. Don't torture yourself about what you think you 'should' be doing/feeling. Be kind to yourself, and know that you loved him.