First period or miscarriage!?

So I had my son in April of 2018. At my 6wk pp appointment I got the paragard IUD. I had a regular period the following month and then nothing after. Until March of this year. I had started feeling funny. Had constant neasua boobs were sore but didnt think anything of the sore boobs because I was breastfeeding. Then the middle of March I woke up soaked in blood. I thought ok well Im having a heavy period (unusual for me). Then later in the day I started cramping so bad I was crying. I was soaking through my ultra tampons and wearing heavy pads at the same time and was still soaking through those. I had used a full pack of pads and half a box of tampons together with in about 4 hours! That evening I passed a MASSIVELY HUGE ugly looking clot and still continued to heavily bleed. Through clothing and dripping on the floor. Cramping continued and I bled for about 16 days before it finally stopped. Then come April and no period, now here is it May and 20 days late for my April period. Still nothing. No signs of aunt flow. My reg doc said she thinks it was just a heavy period because there isnt a positive beta test on file and because I was nursing and weaning it would kick start my cycle back up. Well my son has been weaned for almost 2 months and I still have no period. What is your thoughts? Just a heavy period (one time in a year and nothing since) or a miscarriage?