Not detecting FH rise

Hi, I've been using the clear Blue fertility device for 6+ months now (we've been trying for 19 months now) It's always just shown "high" no FH surges, I have PCOS so my cycles are all over the place, however I do have a period every month/5/6 weeks. Am I just not ovulating even though I am having periods or is my machine not detecting properly. The tests are so expensive, just feeling quite disheartened. Any ideas greatly appricated