another brand, different result

hi everyone,  wanna ask something. 5days ago I was doing a pregnancy test and it come back BFN, then 3days and 2days ago I did it again it come back a vvvvfl for the 2nd line.. then I change to another brand this morning and it come back BFN.. actually I did a pregnancy test 4th times..and the last one by using another brand..it's that mean I'm not pregnant at all? or should I test using the same brand? anyway my af is due on Jan 13th or 14th.. 1St pic is my 2nd test 3days ago with smu.. within timeframe.. 2nd pic is today's test with fmu