Hello.....wow I was pretty much diagnosed today as well.....
To answer one of your questions, no you wouldn't necessarily have the symptoms from the onset of your period. Some women do, while others develop them later. I started having symptoms around 18, they got way worse around 22-25, and I am being diagnosed at 28.
Also, many women with PCOS have children. There are medicines and things that can help you if/when you want a family.
Lastly, don't be afraid to ask questions. I know its hard, since sometimes doctors may not take your concerns seriously, but this is your body and your treatment. You should have all your questions answered. Did your dr diagnose through bloodwork, ultrasound?