Well done YG, I really hope it is a help for you.
IME (when my mum died aged 49, me and 2 sisters were 25, 18 and 13)the period from 4months to 15months was the worst, then things started to improve again. This was certainly my Dad's experience. Facing all those 'firsts' was so hard, birthdays, Xmas,Val day etc.
I think of you and the dds often.x