I'm confused about my period

Raegan

My period is usually normal and I was on the depo shot for 6 months and been off for 5 months now and suddenly in January my period was 16 days late pregnancy test came back negative. Then I had a 3 day period and 2 days stopped bleeding then started bleeding again. Now my period has started in February 8 days earlier then should. Does anybody have any ideas of why this is happening???