Well I’m confused

Ji

Top test is FMU yesterday. vfl but still a bfp. I had a hard time believing it, so I took the digi around 4am this morning after a 3 ish hour hold during the night. Got a negative! Thought maybe I had a chemical so tested with internet cheapies after another 3 hours (did two just in case) and both gave me a bfp. This is the first digi I’ve ever taken. Are they generally glitchy?? Could it be a chemical?