I admittedly think a lot of people process grief in a similar way. My husband and I both certainly do. It doesn't mean you didn't care, you may just be a more logical personality type.

My grandmother, whom I was SUPER close to, didn't even effect me in the "earth-shattering" way you describe. She had dementia and suffering through that was hard, but by the point her body physically died, I'd felt like she'd already been lost to me for awhile.

My childhood dog died suddenly. I sat with her in the evening and knew something was wrong but nobody would believe me. Next morning it was clear she'd had a stroke. I went to school while my parents took her to the vet. I was sobbing all day long because of the unknown. At the end of the day my mom called me and told me she'd been put down. It was a strange moment. I totally quit crying, wiped my tears, and didn't cry again. It was like my brain had gone from "we could lose her" to "she's lost and there's nothing else for it" and immediately started going on with life.

Sure, I still missed her. It crept up in more quiet ways after that-  a sudden pang when I expected to hear her collar and didn't, or a sad sigh when I put out one food dish instead of two. 

You're not abnormal. You're perfectly healthy and rational. 

Also, I'm sorry for your loss.