Hi,
Try not to worry. There are many benign large tumors. That is large enough you need to have it removed and you should be on your way to a gynecologic oncologist. But, odds are still with you. You can't tell the stage by the tumor size. There are different grades of tumor and some grow slowly and get large and others grow really fast and are sometimes smaller. You just need to get it out. I had a 6cm tumor and was stage 1a. I was 37 at the time. I am 2 years and three months out and still cancer free. Try not to worry and think the worst. Even with a malignancy, there is a lot of life to live after a cancer dx. That is not the message we often get from the media. Do make sure you get to a gyn/onc and get that out before it ruptures. Tumors get much larger than yours and are still ok but the rule of thumb is over 5cm and complex need to be removed. Let us know how it goes.
Please don't jump to the worst outcome without real hard evidence. I think you move too fast to make yourself over worried. There several facts you may want to know.
1 final dx of OVCA is from biopsy
2 you are young so the chance you have ovca is much less than aged women
3 The symptoms you are experience may cause by simple cyst.
4 Please follow up, to get to the bottom of this. I don't think you need to think about survival rates right now.
Best wish
Peace and Love
jun