Organization - Paper Storage

My craft room is a 12x12-foot room on the main level of our home.  Granted, the room is box shaped, but it has interesting quirks features to work around.  The door is on an angle and there is a large 8-foot wide bay window across the front of the room.

Like most of us, I'm starting to run out of space in certain areas of my craft room.  I often think that maybe I am not using my space as efficiently as I could be, or maybe there is a better solution that I just haven't found yet.  I'm constantly on Pinterest and other blogs looking to see how people organize their spaces.

Paper is my challenge right now - at least storing it.  I'm constantly adding to my supply, since the company I purchase most of my paper from (as well as most of my stamps, ink, buttons and ribbon) continue to add new colors to their line.
I pretty much use only three different types of solid cardstock: Papertrey Ink's 110 lb weight (for cards and any paper crafts I make that I give away or need a higher weight paper for), the Michael's brand Reflections 60 lb weight (for anything I make with my Cricut as I am not able to get nice, clean, consistent cuts using PTI paper), and a very limited amount of American Crafts textured cardstock I purchased years ago simply because it was 70% off.  It's all just preference, I guess.

For a few years I've been storing my 8 1/2 x 11 sheets of PTI in this Paper Storage Cube System.  I purchased two of them initially and stacked one more section later.  Ideally I'd like to add the additional three sections which I have, but the unit would not be very sturdy if it went any higher (and I am out of floor space to use them as well).  I have my tower currently holding 34 different PTI colors, a space at the top for miscellaneous items, one space towards the bottom holding a Reflections 12 x12 pack (until I find a few home for it), and two open slots to expand for PTI.  Even though this tower is ideal for me, I am going to run out of room quickly!  My lower weight paper did share some space in this tower, but PTI forced them out.  I found these Cropper Hopper 8 1/2 x 11 Paper Holders last week and purchased a few of them (shown in the first photo).  I've decided that anything non-PTI will be stored in these holders, which are then placed in my Ikea Expedite.  This of course leads to another 'problem':  will all this paper overtake the storage I have in my Expedite?  I fell like I'm in a constant live Tetris game with my craft room!