There are medical conditions that could give you a false postitive result, maybe even a faulty test if you had tests from the same batch/pack. However, both of these are highly unlikely and sending a urine sample to the lab has plenty of opportunities at various points for human error to step in.
Go to your local family planning clinic where they will test you on the spot. In my neck of the woods you dont have to give a urine sample after having done a home test. Your next step would have been straight to the midwife here.