You once asked me that question and all I could answer was, "I just love you." My answer to your question might seem so simple, but believe me when I say it's more complex than that.
My love for you is too vast, there's no amount that can measure it. It is by itself indescribable, no words can do it justice.
I would say that you're my whole universe, but to me you're more than just an immense number of galaxies. I would say that I love you to infinity, but I know that I love you more than what's beyond the infinite. I would say that I could love you for eternity, but to me even eternity seems like a short period of time. I could write this for as long as I want, but I know that this won't even be enough to explain my love.
So dear, if you ever ask me again of how much I love you, know that my answer would still stay the same. Within those four words my love remains indefinable. Within those four words my love remains immeasurable.