@Vodkacranberryplease I agree with OP, you are very lucky to have got rid of your bugs in one go using a steamer - except that's not what you did, is it?
You refer to 'bedbug spray', 'smoke bombs' and a 'special mattress cover' and are weirdly non-specific about what any of these are, while being very specific about the brand of steamer you recommend. You also say you used DE and bug interceptors. It sounds like you threw everything at it all at once so it's difficult to say what worked.
OP has been dealing with bugs for 2 years now and has had at least 6 treatments from a professional company that uses steam and DE. She says, in the past two weeks I have caught and killed about 30 live bed bugs on my son's bed (this is despite buying a brand new bed three months ago), and about 10 on my own bed. (though haven't found any for over a week now, though am still getting bitten)
So steam and DE don't appear to be working very well.
They cant hide very deep
They absolutely can! This is the biggest reason not to use 'bug spray' or smoke bombs. They are increasingly immune to all licenced pesticides these days. These products are far more likely to just piss them off and cause them to scatter - behind the skirting boards, into nearby furniture, electronic items, under the edge of the carpet, behind electrical sockets, into other rooms ... this is much less likely to happen with steam but they will still run away from heat if they get the chance.
OP, it's surprising you are still dealing with so many bugs after all this time - could they be coming in from a neighbouring property?
Steam is definitely useful for killing lots of them very quickly. If you don't have a steamer you can lay a wet towel over the mattress seams and press with a hot iron. You only have to heat them to 60 or above. Hot soapy water and a scrubbing brush is effective on hard surfaces like bed slats.
As for Cimexa heres what Google says
Like diatomaceous earth, CimeXa is a residual powder that clings to bed bugs that come in contact with it.
Yes this is true, I already said this. As I outlined above, the difference is cimexa kills them in 2 days instead of 10. You don't have to get it deep into the mattress seams, you don't even need to know exactly where they are living. You just need to put it where they will have to walk through it because as you say, it clings to them.
Never mind what google says, here are the results of lab and field trials of cimexa:
www.pctonline.com/article/pct0814-silica-gel-research-bed-bugs/