Hi Lyn, like you I went through a period of peace, mum died in August, and like you other than that night she died in front of me and I couldn't save her I thought I was coming to terms with it, I would smile at memories etc, but like the others say it is so up and down and if you feel yourself going down again that's okay too, work is a doubled edged sword, it does get a routine going, but the effort of being " normal" for others can be very wearing and trying, every second of the day your emotions change, I cried in Tesco today as I always used to look little treats to take to her, like you I was aware Mum wouldn't have much longer and I worried about it a lot, I doing think you grieve early, you grieve at that time for the person you know them to be is not there, but losing the physical presence is another matter.
Take care x