I totally understand what you are going through. There is not one day that passes where i do not think of my dad. I was ten when my father passed, years later and i still find it hard to cope.
Things that help cheer me up are thinking about things that I can do/accomplish that would have made him smile and be proud of me. (before doing certian tasks i say "this one is for you dad.") But then there are the times when i really do wish he was present for a certian event, then i get depressed... but just keep reminding yourself, he is always there watching over you and smiling.