can this be implantion bleeding?

please help

my period was December 20th 31 days and my ovulation day was January 6 and implantation was date January 15 ..... and it did come on January 15 I was supposed to receive it on January 20 the earliest I get it is January 19 but I bleed very lightly on jan 15 and the 16 I started bleeding very heavy and it stopped on the 17 and started spotting on Sunday the 18 and til like Wednesday21 or Thursday 22 can this be my period or implantation and yes I took a pregnancy test it was N but it just Dnt feel right