I lost my husband nearly 3 years ago. I was very numb sometimes after he died and others I cried until I couldn't breathe. It came like waves.
TBH, I don't really remember much about the first 6 months after he passed.
I think we all grieve in our own way and in our own time. When it is your time, you will cry...as you need to. And not crying is not at all a reflection of how much you loved your Dad.
Sending healing thoughts and prayers to you and your family. Please come here and vent or talk any time.