Please help

So I had a baby 4 months ago. A beautiful little man. That made my 2nd boy. I went on the mirena 6 weeks later I bled so bad with the mirena that I had it taken out. On July 17 it came out and I started a normal period on the 18th. It lasted 5 days. I started bleeding two weeks later and it seemed like a normal period. Lasted 4 days. Now I haven't had a period and if the last time I was bleeding was a period I should have started on the 31st. I used to have 28 day cycles.