@ickihun,
Even though, I have now lost a lot of weight.
A lot of my gradual weight gain was due to excessive insulin converting to visceral fat.
I know you have heard all the reasons for it and no matter what you do or eat, you still gain weight. The reason is not how much you eat, it is usually some food or drink that triggers the excess insulin, it could be anything, and if I have learned anything, it's that it could be anything including protein.
Unless you obsessively test and record everything you might or might not find out.
Also, having PCOS and your thyroid will not help with your other hormones.
A family member has the same issues, with general anxiety disorder on top, but she has one hyperthyroidism and one hypothyroidism to deal with, she has lost a little but rebounds quickly if she eats more than her body needs and creates more insulin, cortisol and her hormones are all over the place especially during that time of the month! (Hate discussing woman's things!) She has been eating very low carb and feels better but the weight goes nowhere!
Insulin resistance will not go away until you get really good control of your hormones, and that is so difficult to find out why you react to something that can't possibly put weight on but it does!
If I remember fasting didn't work for you or you feel awful after a while.
That's what got rid of my insulin resistance and started my weight loss and once I started it fell off quickly. I learned a lot from my fasting stay in hospital and how good I felt and how rejuvenated I was and the energy levels were something to behold.
Just by fasting for a few days.
I still fast intermittently, because of my working life.
You may have to rethink your lifestyle and see how you do experimenting with foods that you don't think would spike you.
I'm just thinking outside the box to try and help you.
I could be totally wrong though!