Basically when your ovary is ready to release an egg a follicle will appear - like a follicle that hair grows from on your head, and this is where the egg comes from. Multiple follicles could mean you're releasing multiple eggs each month (I have twins so that happens to me too, although I didn't know it before!). These follicles can become cysts, and if have multiple cysts that's known as polycystic. This can be a symptom of polycystic ovarian syndrome which is a hormonal issue really. Sounds like they can see this is potentially an issue but no cysts as yet.
I don't have PCOS so I'm only going on my understanding after having countless scans over the years!
At your age, ovarian cancer would be beyond unlikely - not impossible, it happens, but if your scan and blood tests didn't show any of the markers then I would not be overly concerned about this. How long ago was the scan?
This is where it gets complicated as pretty much all gynae conditions have many symptoms in common so it's very difficult to get to the bottom of things.
At your age, I'd guess endometriosis will be their main suspicion and go diagnose that you'd need a keyhole surgery. In fact when you see the gynae I'd push for this if they're not suggesting it - there are many things that can't be seen on a scan (endometriosis deposits, scar tissue etc) so can't be diagnosed or ruled out. Some consultants will simply try to put women on a hormonal medication right away without diagnosing them which I'd strongly advise against - if you have this you really need to know about it and not just treat the symptoms.
Hang in there - I know it's difficult, took me 10 years to get a diagnosis which is not at all uncommon.