My periods have been irregular ever since my mmc in July. Not irregular in cycle length, just in the amount of bleeding. They are still coming every 27 days per usual but the bleeding has varied each time. A typical period for me starts with 1-2 days of heavy bleeding, 2 days of medium bleeding and 2 days of spotting that lasts 5-6 days. My first post miscarriage period was really light like yours, only lasting 3-4 days total. My second was super heavy until literally the day I stopped and lasted 7-8 days. This cycle (the one I'm on) lasted 8-9 days with 3 days of heavy bleeding followed by 3 days of medium bleeding and ended in 2-3 days of spotting. As for ovulating, it all depends. Some people do, others don't. I unfortunately didn't the first two cycles I had but this cycle seemed more "normal" in terms of the bleeding than my first two, even though it lasted longer, so I'm hoping I'll finally ovulate this month.