Depo... bleeding

So I posted a couple weeks ago asking people when they had their first period after getting off Depo provera and mostly everyone said years... well I was on Depo for 2 & a half years just got off shot in July 2017 and then in August I had a period a heavy period for about 4days ... I thought it was over.. didn't bleed for two days then out of nowhere there was dark blood and that lasted another 2 days... another 3 days has gone by and I'm having even DARKER blood and I'm so confused what's going on. It's been around 3 weeks of bleeding now and I'm not sure what this means... am I alone in this or does anyone have any advice or idea what it could be.. thanks.