False negative Covid?

So I’ve had two negative Covid tests Done last Friday. When I felt bad with a URI. They were both negative. Now my nose is super dry but also so stuffy at the same time m. So obviously when I woke up I couldn’t smell anything. But the wether is changing a lot in Texas. It was 80 degrees yesterday and cold and rainy today. I feel fine now with a sinus headache and a few coughs here and there. I’m still on antibiotics for the URI. Could both my tests be faulty? Some they were negative I was able to return to work but I’m freaking out now because what if they were wrong and I’m unknowingly spreading it? Insurance covers the first two but said they might not cover if I get another in the next two weeks. Do y’all think I’m okay? Maybe I’m just freaked out. Not to mention I haven’t been exposed to anyone at all. I work alone, masked outside, and customers stay 6+ feet away.