I don't have PCOS but have done a few rounds of detoxes lead by Dr. Sara Gottfried, who has written The Hormone Cure and The Hormone Cure Reset Diet, and many of my fellow detoxers have PCOS. There is lots of info on PCOS in The Hormone Cure and on her website, with practical advice on how lifestyle changes (diet, supplements) can mitigate symptoms and restore some of the normal balance to your hormones.
I think if I were in your shoes, after seeing your own doc I'd get a copy of The Hormone Cure book and if your doctor doesn't practice functional medicine, I'd seek out someone who does as they tend to have more in their took kit than pills and surgery. Hormone imbalances can trigger so many symptoms throughout the body so you want someone who can help you heal your body from the inside out - not just with synthetic hormones like birth control pills that treat one or two symptoms or with removing your organs but with nutrients that get your body where it needs to be to sustain good health from head to toe.
All that said...period changes after having a child are very common. After my last pregnancy, it took almost a year for my periods to get back to somewhat normal. Mine were close together, long and very heavy. I was also feeling very hormonally out of whack - cranky, angry, gaining weight, acne, etc. I went to my doc to see if she would send me to an endocrinologist or prescribe a progesterone cream or order hormone testing. She didn't do any of those but instead prescribed Prozac and birth control pills and told me to see my ob-gyn, whose solution to the heavy bleeding was to offer endometrial ablation (literally burning the lining of your uterus so that you no longer have periods). Luckily I didn't follow the advice of either of them and was back to relatively normal on my own a few months later.
The pressure in your pelvis could be something like uterine prolapse (the uterus descends lower than it should), a cyst, etc. so hopefully your doc can to an exam or order imaging that explains what's going on with that. Hope you get some answers soon!