I'm terribly sorry to hear of your loss.
Grief is normal. It's even healthy. It's also something that is unique for everyone. People experience it differently, and you shouldn't analyze how you're experiencing it too closely, or compare your experience with other people.
I lost my father a couple of years ago, and it was tough. I didn't cry, or fall apart, but even after all this time, I'll think "I should call Dad, he'd find this interesting," or something like that, and I'll pause, and grieve a little bit. I also know people who lost their spouse, and were quite muted or stunned by everything, only to have grief overwhelm them a year later on their spouse's birthday or on their anniversary.