Is mattress on the floor the safest?

Does anyone here sleep on a mattress on the floor? I’m at a loss for what else to do. We have a bedroom set, and our bed is sort of high. My worst nightmare happened this morning when I woke up to crying and saw my 12 month old had crawled off the bed onto the epoxy/concrete floor. We went to the ER, and she’s fine. A large hematoma on her forehead. I still feel incredibly guilty. I always wake up before her, but didn’t today. I was so exhausted from waking every few hours while she’s been sick☹️ I feel awful for not protecting her. We just moved and I’d been meaning to order some side rails because I knew something would happen, but failed to. The problem is that I cannot find any that are tall enough for how big the mattress/box spring is. I’m considering getting rid of the bed frame and just sleeping on the mattress. Does anyone here do that, and could you show me how your style it? Or does anyone have any other suggestions that still allow co sleeping? I want to do whatever will be safest for my daughter. Thanks.