Jenn.
I completely understand your feelings. I would have really rough days without explanation after Mom's passing. I think in part, I was trying to keep my mind preoccupied so as not to feel overwhelmed. Time alone doesn't make it go away though, it just prolongs working through the grief.
It took me months to really allow myself to grieve but I can honestly say that feeling the pain of my loss, allowed the space for happiness to replace it. The fog that I was living through has lifted greatly. Processing your loss and allowing the emotion will help you through the understandable sorrow of your dad's passing.
Part of a post from Daughter01 has stuck with me... "Be patient with yourself and your emotions ..." I would keep coming back to this as I coped with Mom's death.
Please be patient with yourself in this time.
Thinking of you.