Possibly miscarriage

I need advice. Help! Last month I had a strong sense that I was pregnant. I’m 6 months postpartum and I was freaking out. My period came two weeks late and was super painful and heavy and long. Ever since my period ended two weeks ago, I have been passing tissue with blood in it, usually when I pee. I have also had some spotting. I wonder if I had a miscarriage. I have no idea what’s going on.