How do I tell my girlfriend that I think she might have PCOS?

My girlfriend and I have been together for about 3 months. She is amazing and I love her very much. However, I truly believe that she might have PCOS. She mentioned that she once had a period lasting a full month and that she suffers from irregular periods sometimes. Furthermore, she has a lot of trouble losing weight despite the fact that she eats way less than me. Her weight accumulates around the midsection, rather than the hips, which is a symptom of PCOS. Given that over 50% of PCOS cases go undiagnosed, I believe that she could be suffering from this condition. I've tried to bring it up to her before, but she is in denial about it. I don't want to hurt her feelings, but I am also worried for her health. Is it possible for me to ask her to get checked for PCOS, without making her angry or sad?