Which day did I ovulate?

Nikki
Hi ladies! This is my first month charting so I need a little help.
I got a positive OPK on CD 18 and my temp rose on CD 20. Both FF and Glow are telling me I ovulated on CD 19. But you can see that I've had a few temps as high as my temp on CD 20 this month (which I discarded because I had drank the previous evening) so I'm not sure if this counts as a true thermal shift.
Yesterday I had a TON of EWCM and I just saw another sharp rise in my temp this morning. Is I possible that I ovulated on CD21 instead of CD19? Anyone heard of an LH surge three days before ovulation? Now I'm worried because we didn't BD yesterday. 😢