I am sorry you are dealing with this. The good thing is that most ovarian cysts are benign and most resolve on their own. However, these sound like the type that do not go away so need to be surgically removed especially the larger one due to size. According to radiology websites, hypoechoic cysts are usually endometriomas or teratomas (dermoids) both of which are benign (non-cancerous) cysts. Of course, imaging is not exact so they cannot know for sure until they do surgery.
The CA125 test is not a good tool for diagnosing cancer. Benign conditions, including benign cysts, can cause an elevated result.
The good thing is that your gyn plans to do a cystectomy (cyst removal) which would preserve your ovary. Far too many women lose an ovary, both ovaries,and even all their sex organs unnecessarily (yes, it even happens for benign ovarian cysts being the only problem...happened to me). We need all our organs our WHOLE LIVES not only for fertility but for overall health. Ovary removal as well as hysterectomy (uterus removal) are grossly overused in the U.S.
If there is any concern about cancer, I would hope your gyn would recommend you see an oncologist. But regardless of who does your surgery, you will want to protect yourself to ensure that they remove just the cyst and leave all your parts if the frozen section biopsy done while you are in the operating room shows that the cyst is benign. You can do this via the surgical consent form. Keep in mind that not all gyns or gyn oncologists have good cystectomy skills so will remove the ovary unnecessarily. I wish I had done things very differently when I developed a 9.5cm cyst.
Best of luck to you! Keep us posted.
I forgot to add that I am 27 years old.