Positive OPK & ovulation signs - no temp spike?

Hello All! I have a situation that I'd love some advice on! On cycle day 15, I had a positive OPK. I had about 8 high fertility days leading up to the peak. My CM was fertile & I just felt like I was definitely in ovulation mode. Today is cycle day 18 and my temperature has still not spiked. I have been TTC for about 6 months and it always spikes before now. Any advice or suggestions?! 💗