Trying (and failing) to crochet a rug

I’ve started this particular rug over so many times because I can’t seem to find a good way to get it to not warp or bubble. It’s not easy making a rug without the tension a frame offers, but I’m convinced I can do it, I just have to work out a) what I want and b) how to accomplish it. This is supposed to replace our breaking kitchen rug that sits under the stove. That means it needs to be sturdy and ready to be washed often. But as I keep having to frog the whole thing when it starts warping, I may just have to look into some kind of loom if I want to make it like this.

Each and every one of these pictures is a new attempt: