Why is my period so much different this month?

Lemme just be clear that I’m not worried about it or anything, I’m simply curious about the biological reasons behind this. Here it is: I was on the pill for 2 years until January, then I stopped taking it. On birth control, my periods were always so light I could hardly wear a tampon. When I stopped taking it, it continued that way. But I’d get really bad cramps. I have always had bad cramps, since I got my period at age 13. Terrible cramps. They were worse when I was younger, then they got to be bearable, and the past few years (and on BC especially) they were virtually nonexistant as was my period in general. So that’s the way it’s been for almost 3 years now. Then suddenly, this month, I get my period, with absolutely no cramping (not even the mild cramps you get a couple hours before your period starts that kind of “lets you know) and it is honestly the heaviest period I’ve ever had. But it is completely painless. But there is SO MUCH BLOOD. I have never soaked through a Super tampon in 4 hours before. I never even buy them. I don’t even know why I had one. But I did this morning! And it’s the 3rd day of my period!

Anyhow, enough details. I’m just curious as to why this would happen. Thanks.