My heart goes out to you and your family, LG. It's never easy to lose a loved one, and sometimes it's downright unbearable. Sometimes it takes a long time for it to sink in, and in the meantime you may feel guilty for not feeling what you think you should. I cannot offer any anecdotes (while I have lost many friends and family members, none were so close to me as one of my parents) but what I can do is remind you that your father's spirit will live on. Even if you don't believe in heaven or some other spiritual realm, he is still around you all the time--little bits of his life that he dedicated to making a difference, his work around the house, his posts here on the forum, your memories, and most of all, you and your siblings. You have the awesome privilege of being a strong young man who can keep his memory alive and can be the son that he was and will always be proud of. He lives on through you, LG. I'm sure you will continue to do him proud by pursuing your interests and excelling at them.
Just remember that your father is not lost. He is still here, and always will be.
Best wishes and warm regards,
Matt