PCR tests can fail if the original sample isn't taken well. They can also provide positive results long after an infection as they pick up just the remnants of th virus.
The quick lateral flow tests aren't very accurate at all so false negatives are quite possible.
Ultimately, it's quite probable that you've had the virus and recovered. Some people don't seem to transmit the disease much for some reason - the opposite of 'Superspreaders', so this could well explain the lack if infections for your contacts. Alternatively, they may already have immunity due to previously undiagnosed infection! Lots of possible explanations for your confusing run of test results.
The quick lateral flow tests aren't very accurate at all so false negatives are quite possible.
Ultimately, it's quite probable that you've had the virus and recovered. Some people don't seem to transmit the disease much for some reason - the opposite of 'Superspreaders', so this could well explain the lack if infections for your contacts. Alternatively, they may already have immunity due to previously undiagnosed infection! Lots of possible explanations for your confusing run of test results.