How can I get rid of bed bugs for good?

Ok something isn't right here. You should not have to have them come back 4 times. Flip through the yellow pages for a specialist that specifically treat bed bugs. Heat is what draws them out. I totally understand too. My brother is also asthmatic and I have a bird - so I get your concern. See if this helps.

https://www.epa.gov/bedbugs/local-resources-bed-bug-assistance

https://www.bedbugs.org/bed-bug-exterminators/

Diatomaceous earth causes insects to dry out and die by absorbing the oils and fats from the cuticle of the insect's exoskeleton. Its sharp edges are abrasive, speeding up the process. Bed bugs lay hundreds of eggs in cracks and crevices, which hatch every 6-10 days, so I would try treating them every week for a month. Here's an article on how to treat bedbugs with DE. With your breathing problems, you would want to use an abundance of caution if you decide to try it. https://www.zappbug.com/get-rid-of-bed-bugs/bed-bugs-diatomaceous-earth/#tab-id-1

This article may help https://www.doyourownpestcontrol.com/bed-bugs.htm

Even when your house is treated with DEET it only offers 14 day protection. I would put a bed bug mattress cover on the bed.... https://www.amazon.com/s?k=bed+bug+mattress+cover&crid=218PLWPCX3EYS&sprefix=bed+bug%2Caps%2C473&ref=nb_sb_ss_i_1_7

I would also do some early intervention like putting bed bug traps around https://www.amazon.com/s?k=bed+bug+detector+trap&crid=38YXT1C4AF84R&sprefix=bed+bug+detector%2Caps%2C214&ref=nb_sb_ss_i_4_16

And I would also have a UV light to detect them.... https://www.amazon.com/LOFTEK-Ultraviolet-Flashlight-Handheld-Detector/dp/B007SIR08C/ref=sr_1_8?crid=38YXT1C4AF84R&keywords=bed+bug+detector+trap&qid=1564798967&s=gateway&sprefix=bed+bug+detector%2Caps%2C214&sr=8-8 the egss hatch every 6-10 days

Be mindful that any soft surfaces like clothing can also be infested... we had a whole building that was infested by a woman who collected clothing and fabrics from second hand stores. Wash anything that comes in your house.

An alternative to bug sprays is heat treatment.... https://www.bedbugs.umn.edu/homeowners-and-tenants/understanding-treatments

Tks!! Appreciate the advice!!

I use a Karcher steam cleaner on mattresses and carpets. They’re dreadful pests and the bites get infected and can last for many months.

Hi Barbara, hope this helps you out,

https://www.healthline.com/health/healthy-home-guide/how-to-get-rid-of-bed-bugs#contain