You poor thing! I've just had one ridiculously heavy period (so heavy I thought I must be having an early miscarriage as it was the same as a miscarriage I'd experienced years ago). If they were all like that, I don't know what I'd do! Interestingly, the 2x I've had a 'period' like that have both been after using Metformin. Like you, it doesn't seem to agree with me. Not the GI side effects that are so common with it, I don't seem to get those, but extreme lethargy, weight *gain* and these flooding periods.
My periods used to be heavier than normal when I was cycling regularly (that was one other charming side effect of Metformin - when I took it the first time, my 6-8 periods a year instantly disappeared completely for 3.5 years). After I decided Metformin just made me too ill, I started taking Vitex Agnus Castus to regulate my reproductive hormones and D-Chiro Inositol to help with insulin/blood sugar control. I take a few other things too, but those two are the main things that I seem to go haywire without. Anyway, since I've been doing that, I've slowly been losing weight (which I could not do before), and my periods have been 'normal'. Not quite a 28 day cycle, but I'm back to having about 8 a year which I'm perfectly happy with for the time being.
It's really hard not having a competent professional you are able to turn to to help you manage PCOS. I'm in the same boat. And I share your frustration at watching people stuff themselves with all sorts of rubbish and have their properly functioning bodies just deal with it, whilst you are so careful it's close to obsessive!
For me the answer was becoming a PCOS expert myself. Being a bit of a control freak, it help me cope better by understanding what was happening, what was causing what and what I could do to influence it all.
Good luck! I hope you find the answers you need.