Bed sharing and wall

We moved our bed to the floor when LO started crawling around and standing to avoid any potential issues with him falling off. We still have a high mattress, it's 18in, but it's better than when it was on the box spring and bed frame. I didn't move the crib mattress to the floor because it's so much thinner than our mattress.  

We set it in the corner so there's a wall on LO's side and then me then H on the outside. Since H works nights, I usually start the night next to the wall so LO can nurse off that side, then flip when he wakes up for his middle of the night feeding and H comes to bed. I've never been able to nurse the topside comfortably enough to stay on one side all night. It's less disruptive for me to just move.

LO is a busy sleeper, he flings himself around in his sleep and has even ended up upside down with his feet on my chest and head at my knees. Last night I had moved to the middle and LO was stirring but still sleeping. He rolled to the wall and then tried to roll more and hit his head really hard. He was crying and pretty upset. I felt terrible. He spent the rest of the night curled up against me, and it didn't happen again but now I'm worried we need to change our set-up.

Freak accident or should we move the bed? If we should re-arrange things what do you suggest?