I am so glad you asked this question. I have been feeling this way for a long time. I have been praying to God about it. Now, when i feel this way, it draws me closer to him. So i came to believe its the longing inside for God. I know you love him and are with him, but we are still far from him because we arnt in heaven yet! Once we are in heaven i think that feeling will be filled. Im not positive on this and im still praying, but i know i feel that way and hate living on earth because i just want to be with Him in heaven. So im patiently waiting and doing his work untill i may be rewarded in that wonderful place.