Steve,
Thoughts of your dad will always be with you, as will his comforting presence. My father passed away 13yrs ago. I was in a fog for 3months or so, but as you say 'time is a great healer.' Tougher for spouses, my mother died last fall and while she became more comfortable without Dad the last few years, he was always on her mind and she missed him deeply.
It can be tough to move on sometimes, but that's what we do; change is life. I think often of a corollary sentiment on a sympathy card I received at my mother's death - "Life is changed, not taken away" Your father has moved on to a wonderful 'adventure', we'll all get there someday.
God's Peace