I’m on CD 15 and still nothing on OPK. Not even a faint line. I have been testing twice a day since CD 8 but I feel like either I didn’t O or I missed it on the opk. I had ewcm for a few days and libido was high around day 12. I think I saw very faint lines around those days on the opk but now there is no second line at all!! Sooo frustrated. I’m thinking of buying the digital test where it tells you your ‘fertile window’ but they are so expensive. Any tips, this is my first month using these.