I can understand your concern. Just know that most cysts turn out benign and the fact that you are suspected to have PCOS makes it even more likely it is benign. But, recurrent cysts are hard to deal with and I was also plagued by cysts since my early teens. So, I do understand your concern and frustration with being sick. I felt the same way!
The key with your current large cyst is to know if it is simple (fluid filled) or complex (has solid parts). Simple cysts can be drained or watched to see if they go away on their own. Although, most doctors still like to remove them once they are 5cm. Complex cysts are little more tricky because they run a small chance of being malignant. Still, the majority of them turn out to be benign. But, there is no way to know for sure without removing the cyst intact and having it biopsied. So, if yours is complex, I am sure they will want to surgically remove your cyst.
This larger cyst will have to be evaluated and dealt with on its own. But, into the future, you should definitely work with a doctor who has experience with PCOS. Certain gynecologists and endocrinologists have more experience than others. Medhelp has a PCOS forum that you might want to check out. Here is that link:
It is good you are seeing a surgeon. Usually, a gynecologic oncologist should be consulted prior to surgery if you have a large, complex cysts. That way, if frozen section during the surgery determines the mass is malignant, the gyn/onc can look around the abdomen and evaluate areas of concern. He/she will also be able to complete the staging during that same surgery which is very important for ovarian cancer treatment. I really think your odds are extremely low that it is malignant. But, you should discuss this issue with the surgeon if you find your cyst is complex. It is always better to have discussed all options prior to surgery.
So, please try not to worry. But, know you are normal for being concerned. You have already been through a lot and it is always stressful to be facing surgery. Please give us an update after your next appt.