3 months post mirena removal

So here's my story,

I had 5x miscarriages with my previous partner. We split, I got with my, now, husband and went straight onto the mirena coil, which I found out I had pcos around the same time. I had it in for 3 years and had it removed the beginning of Dec 2017. My periods have been spot on to the day for 2x cycles, i know I ovulated as I charted. But this month, it's gone crazy. I'm now 7 days late for my period and have been having crampy, dull stomach/uterus aches since the day I should have started my period, but still nothing. Oh and I did a test 5 days of missing my period and it was negative.

I'm really looking for any advice at all as it's driving me mad!