ROM slots weren't moved in 3.5x. Your original 4 should all be there. And you can now see the sizes of each slot if it's active. Is there a chance you made the 1st slot a 3GB data size which is using all your room?
I've never allowed for creating ROM slots on the external SD card. Sorry
I just figured out what happened with my memory. After recently undating to jellybean 4.1.2 from ics 4.0.4 I'm having problems utilizing my external sd card memory. I'm not even able to move apps to my sd card. By default my internal memory is only being used so I moved everything off my internal sd card to make room to create rom slots until I can figure out how to make my 64 gb sd card memory the default as I was able to do on ics