Whoah, I'm moving the TWRP nandroids to my PC. Not sure how big they are but it's taking forever to transfer (vs a few sec for the CWM ones). I'm guessing that's where all the space is taken up.
Let's hope that solves the problem.
Edit: yep, they're 2.3gig each!
Wipe em off (don't need them as I'm already stock) and start over.
Thanks for the help everyone.