+ OPK but no temp increase ?!

Brittany • Mama to 2 girls! 💗 🤰🏼 with number 3!
So I got a positive OPK on cd 13 & 14. But my temp hasn't adjusted at all like it did last month when I got positives. I usually don't ovulate until cd 18/19.. Do you think I just had a surge and will ovulate later this week? Ugh confusing !