I cannot believe it has been a year already since your Dad passed away, I do remember, and please know that I am thinking of you. I don't know you really, but I know that you are strong and you will pull through. Try to do something soothing or pleasurable for yourself Take care, we are here for you!
My therapist once told me that subconsciously our mind remembers those dates & reacts to them. Anyway, it's only been a year & I think it is part of the grieving process to remember & feel sad around this time.
I usually buy a single rose and put it in a solitaire vase and light one candle next to it and keep it burning throughout the day on the anniversary of someone's death who is very special to me. Everytime I see it I try to remember something positive about that person. I keep the flame alive all day. When my family see it they ask about it and we all share.
Everyone is entitled to a "slack day" or "mental health day" especially those with mental illness in my opinion, so on those days that I feel like not cooking or doing housework or absolutely nothing I go with the flow. I just have days like that sometimes and love ones around me understand that and pick up the slack for me. As long as we don't let it linger too long (more than a couple of days).
Thinking of you and sending ((Hugs)) during your time of sadness.