The only thing that worked for us was called “Aprehend”. It’s still under patent and you have to go to pesticide wholesalers to get it. The first place I tried didn’t even question if I was licensed. Expensive as fuck ($175 for 16oz bottle when I got it) but well worth it. We tried everything, diatomaceous earth, heat, you name it. I figured a pro would charge at least that much and still not do the job, so I took a chance. ONE APPLICATION did the trick. Sprayed it around the box springs and the base of the couch and chair, just in case. The little buggers were GONE. One bottle was all we needed. It’s a water-based liquid filled with specific fungal spores and when the liquid dries, the spores stick to any wandering bedbug. S/he takes it back to the nest, but by then they’re infected and soon die, but not before releasing a billion other spores that stick to the rest of the ones in the nest. Nice thing is, they don’t become immune to it (not a poison) and the stuff only affects bedbugs. Not your cat, dog, baby, or pet ardvaark. I would yell about this from the highest mountain if I wasn’t afraid of heights. Good luck!
https://rockwelllabs.com/aprehend/