I'm also 42 and have never been pregnant, either. And, so far no improvement with my menstrual stuff on iodine. They are still long, heavy and clotty, like they've been since I was 16 or so, and I think I have some other long term hormone imbalance that Iodine is not solving. I am actually having a circulation issue now with my legs and feet that I suspect is a combination of Raynaud's (apparently goes with thyroid) and blood stasis originating in the pelvis. I did some reading on pelvic congestion and apparently you can actually have "varicrose veins" in the pelvic region, and I'm wondering now if what I've been assuming is endo and/or fibroids is actually a problem with my arteries and veins around all my lady parts. The massive amounts of sitting I do for work have not helped the situation. I suspect I was prone to this from the start, but made it worse by my choice of profession and laziness about countering it with enough exercise.
I don't know if there are any similarities there with your situation. Also, I do think we are at an age where we are likely to see some menstrual changes, whether that's normal or not, I don't know, given the toxic planet we live on and how loaded we might be with xenoestrogens, etc.
Oh - and here's something - this happened to me twice in the past few months - I was taking Floridex herbal liquid iron supplement on Dr. Brownstein's recommendation because I had signs of anemia, and both times after using it for about 10 days, I got my period early. Actually the first time it was like the previous period never really ended with spotting and sore boobs, pms, etc. until the next one that came 10 days early. I stopped it for awhile, but this month I tried it again and while it didn't start my period full on, I got some spotting and that more swollen feeling. I stopped the supplement again, so we'll see if it still comes early, but I know I have had this happen in the past when taking any herbs that have an estrogenic or adaptogenic effect - like dong quai, ashwaganda, chaste tree berry, etc. The Floridex has fennel, which i've read is weakly estrogenic. Supposedly that kind of thing helps balance hormones - weak estrogens, but it never has that effect on me, always throws things out of whack.
I'm also on the fence about whether a menstraul period is really for the purpose of cleansing, and whether an extra heavy one means the body is dumping toxins. As someone who has bled like crazy for all my adult life, I don't feel any less toxic as a result. My hunch is it's more about endocrine balance, what triggers that kind of activity. There are a lot of hormone disruptors in our environment, and I'm not sure even being full up on Iodine can counteract that.