STOP putting that pressure on yourself!!!
You are happy when she is there, you smile, what more do you want?
You don't stop being an individual, just because you have a partner, so it is OK, to not think about her constantly, not miss her every second, when she's not there.
Because you still have your own life to live.
Just enjoy what you have while it lasts!
My husband (who I love more than anything in the world, apart from our son) is abroad for four months at the moment.
That does not mean, I have to be miserable while he is gone.
I go out with friends, I enjoy myself, but I am also looking forward to him coming back.
That is perfect love for me!