It's impossible to have a false positive because the test picks up the pregnancy hormone which is only there when pregnant. Take the test when you first urinate in the morning as the hormone is strongest. If you got a positive, then a negative it means a reduction in the hormone levels detected, which might just be time of day but could indicate that your body has stopped producing the hormone or is producing less, which might but might not indicate a problem. Best to go to your doctor. Good luck x
Yes as long as you took the test correctly false positives are rare your most likely pregnant. Try a clear blue digital they are easy reliable and clear.
Sounds like you are pregnant maybe still early y one picked up the hormone and the other one didn't I would wait a couple days and re test but a positive is a positive and get a blood test to be 100%