They're basing it on the polycystic ovaries along with the long term acne and somewhat hairiness. I also do have weight on my stomach but it's far from 'truncal obesity' - still, I don't gain wait in my breasts or my thighs or anywhere I want it, it goes straight to my middle which is weird. I guess none of this things alone made them think PCOS, but together with the polycystic ovaries, it looks much more likely.