Does creamy/ lotion type cm come after ovulation? I’m CD15 and started using opk on CD12 but they…

Does creamy/ lotion type cm come after ovulation? I’m CD15 and started using opk on CD12 but they aren’t getting darker so I’m trying to work out by cm whether I may have missed my surge... I often have 25/26 day cycles so wondering whether I may have ovulated prior to CD12 🤷🏼‍♀️