I'm19, not overweight(i'm 52kg) have regular cycle, don't have health problems but i was diagnosed with polycystic ovary syndrome.are pills necessary?

Key question: The key question to answer your question is... Are you missing cycles? If the answer is yes, then you need pills. And by pills, i assume you mean birth control pills? Another component of pcos is Insulin resistance, so maybe you were referring to pills to manage glucose? The answer to that would be yes as well. You are right, though, not all women with pcos are overweight. Good luck!