But you still haven't explained what you mean by 'bereaved' Generally that word simply means that someone close to you has died, not how you feel at their death. Nor have you explained what emotions you think you should feel.
My parents were in their late 80s and 90s when they died, I was not devastated by their deaths, they were inavitable and natural, but I did grieve the loss of their company. Neither had any mental lack of capacity.
My father, in particular, had a wonderful grasp of language and its possibilities, as has DD and any family meal would always include a time when the two of them would start making puns and trying to outrun the other. With my father's death that ended - and we miss him and the hilarity and groans, he brought to the party.
On the other hand when my sister was killed in a road accident . I was devastated, she was only in her mid 40s, her death was sudden and unexpected and we were very close.
if you do feel nothing, think about how you feel othe emotions, love for a partner or child. It could be that you are a psychopath. I am not talking about a media psychopath, red in tooth and nail and looking for people to kill, but just a common or garden psychopath, of which there are many among us, who simply do not feel the emotions that other people do.