would like to test for mold in the house, but I’ve heard those home kits are unreliable. Anyone have any experience or recommendations?
You aren't going to be able to do a thorough check with a self-bought home quality testing kit. Hire a professional if you are truly concerned, they do multiple checks within your home and HVAC system that go well beyond simply walking around with a handheld air quality tester like you'd find on Amazon.
If you have home insurance I'd contact your provider and see if they have any local partners. Otherwise for these sorts of things I do a lot of due diligence online looking for not only reviews, but thorough reviews of what they provide as part of their service. I'd narrow it down to 2-3 and then request a quote and compare a detailed list of what they offer with their check and then make the decision. I"ve used Richmond Air in the past with great results for general HVAC work, but there are quite a few providers with a lot of reviews on Yelp for "air quality." Clean Air Houston seems to specialized in what you're seeking and has great reviews as well. It is also worth checking to see if an inspection will help drop your home insurance premiums a bit. You never know, those savings alone could pay for the service.
You have to be extremely careful with any companies that you hire to test air quality or mold. 1. Every house, especially houses in Houston will have some mold in them and in the air. The question is: is it the bad type of mold that you can actually be allergic to and is it significantly different than the amount of mold in the ambient air of the environment. 2. Since the huge amount of mold scams about a decade ago, insurance and regulation have dramatically changed on what they will pay for any kind of mold remediation. 3. Many mold or remediation companies are STILL scammers and will stick you with large bills that insurance won't pay and are needless work anyways. So I'd be careful. Contacting your insurance company may be the way to go, but you REALLY want to get an air quality company that is trustworthy, otherwise they are going to recommend all kinds of services, repairs, and remediation you don't need.