Ok, here goes. (This is all assuming that you do have PCO and there isn't another reason for your lack of periods.)
Having PCO means that your body doesn't produce enough of the hormones required to ovulate regularly - or, in my case, at all. So the follicles, that in most women will grow and release an egg, just stay on the ovaries (polycystic ovaries therefore being a bit of a misnomer)
When you had the scan did you see what your ovaries looked like on the screen? If you have PCO there would have been little black lumps all over them.
Nobody is going to tell you that you won't ever conceive because there are several avenues for treatment, and the fact that you probably do naturally ovulate a few times a year is a good thing.
The first treatment that will probably be prescribed for you will be clomid, which simulates the pituitary gland into producing the necessary hormones.
If that doesn't work then you might get the hormones injected directly, or you might have ovarian drilling, which is pretty much what it sounds like, though I think that's a less common procedure nowadays.
If neither of those work then the next step is usually IVF. I'm only on my second cycle of clomid so I haven't got there yet - but there are lots of other women on this board with PCO who have been through the lot.
For now, try not to worry yourself too much, you're really young so time is very much on your side. (And all the stats for conception with clomid, IVF etc are better for under 35s) You don't mention if you're overweight but if you are - and it often goes hand in hand with PCO - then you need to try to get your weight down to as 'normal' a BMI as possible as that will help you ovulate (and certain PCTs won't treat women with very high BMIs, though of course that might not be an issue for you at all)
I'm currently being checked out for PCO, a friend described her symptoms which matched mine but until recently it was sort of in the back of my mind. But I've now been for the scan and blood tests and should know results in a week or so. I'm 21 but have only had. 2 periods in the last year and maybe 3/4 the year before that. I'm very scared that I'll be told I won't ever conceive and worried sick. Can someone explain in easy terms to me what the treatments are, or other possibilities? Thank you x.