You will be in my prayers Terri.  I can tell you that there was only one brief moment in my life that the proverbial   "empty feeling"  common to all humans  was called to my complete attention. It was when God lifted and held me and it caught my full attention, because I realized I was filled!
    This is what I pray happens for you, and sooner rather than later.   My question was why do we have it?  But the answer was given before the Question was formed
"Oh little girl, the empty space is my gift to you. "I allow this homesick longing to remind you to always seek Me."