Deep sympathy. Bed bugs are horrific.
It sounds like you have probably cut down the population, but unfortunately it is extremely unlikely to have done the job.
I'd really recommend getting experts in, but be wary of treatments. Spray pesticides can work but tend to 'scatter' them, making them harder to find and spread elsewhere, inuding potentially to neighbours. The bastards can lie dormant for months and wait it out. Heat is more effective but is hideously (££££) expensive and doesn't always work, it just takes one female to survive and you're back to square one. Bed Bugs UK have a really good reputation if you'te vaguely London based, and have given me brilliant phone advice for free.
If you must DIY, try cimexa powder. It is completely non-toxic powder that works by dehydrating them. It works quickly and effectively, you just dust very very finely with a paintbrush. Steam is effective too but you do need a powder too. DO NOT spray, nothing commerically available will be strong enough.
Keep washing and tumble drying, you can dry on a high heat things that don't need washing.
A passive monitor is good for sanity. Don't buy interceptors/sticky traps, they are shit and can make things worse.
Finally, try to avoid binning things. Unless the mattress is torn they don't live inside it, although encasements are nice. There will be other bedbugs around the bed so binning it doesn't really help, it just means they form a harborage elsewhere. You want to let them do whst they do naturally so they are predictable and you can get them with a powder. Scattered bedbugs make life shitter.
chin up, they are fixable.