Progesterone test

Insight needed! I have a progesterone blood test in a few weeks and I'm concerned I have pcos because the <a href="https://play.google.com/store/apps/details?id=com.glow.android">glow app</a> suggested it based on my irregualr periods. The more I read the more I'm worried and I was just wondering if the progesterone test could reveal the beginning diagnosis? I will obviously also mention it to the nurse when I go for the blood work. Thanks in advance!