Pcos and ovulation sticks

Bryony • 23-UK-TTC#1-PCOS

For the past 2 months I have been using ovulation sticks and they always seem to be the same dark colour but never quite as dark as the control line but the past 2 tests have been a pretty much none existent line. Has anybody had this before and any insight as to why now all of a sudden they are light in colour when they never have been?

Thanks!