Your ovaries are very small, so depending on when your last ultrasound was, if it wasn't flagged as being enlarged or having a cyst, I'd also be focusing on the range of other organs it could be. Just that across the abdomen symptoms are often very similar but for loads of conditions, so that's why in the diagnostic process, as much as it makes sense, we should be broad first, to try and not miss anything, rather than very narrow quickly.
If it's just twinges and nothing else, e.g vomiting, nauesa, severe pain, constipation, diarrhoea, etc, then it's likely nothing or not needing extra unnecessary treatment unless you feel its getting worse, impacting your life with the frequency of the pain? I mean push for maybe one more scan like a CT (going to he unlikely as your symptoms don't necessarily sound severe enough but worth a try) or more likely a transvaginal and abdominal ultrasound as well.
So for your PCOS all your bloods like cholesterol etc are fine? That's good then, keep on with that as much as possible, and then the coil or vaginal progesterone is a very good option for your periods if the irregularity is the main issue and it also will help with cramps and less bleeding as well. Are your symptoms just on your period or elsewhere during the month? What symptoms do you have during your period? And if you have symptoms not on your period - is the pain worse on or off period?
For the mirena coil insertion, make sure you take paracetamol and ibuprofen 1h before, then make sure they insert licodaine into your cervix, have numbing gel etc. That way it will be more comfortable for you.