I'm so sorry for the loss of your precious Dad. I understand the pain, the sadness. It's difficult as death is so final and we're left with the memories. Especially since you two were so close. I do think it's normal to feel the sadness. How can we not, when someone who has meant the world to us is no longer physically with us. Our brain knows it's true but it takes quite awhile for our hearts to catch up to that truth.
Not sure I have any advice, I only know that we all grieve differently. Some of us longer than others. There's really no right or wrong way to grieve and there's no time limit.
Welcome to Webhealing. There are others here who are grieving the loss of their parent, also. We find comfort when sharing our pain with others.
Let me know how you're doing.
Sending you a big hug and my love,